Although Goku is typically framed as the hero of Dragon Ball, there are countless times when his judgment is more than a little questionable. Like a child playing with his food, he regularly delays ending his fights which typically puts both people and planets at risk. This is only the tip of the iceberg though.
He may well be the most powerful Saiyan in existence, but Goku is far from the brightest. He's been handed countless opportunities to learn from his mistakes over the years and yet, despite acknowledging them, he continues to put others in danger for his own selfish reasons. This is certainly not the behavior of a hero. In fact, there's an argument to be made that he himself is at times the biggest threat to the twelve universes.
Updated April 14, 2022, by Tom Bowen: Goku has fought more than his fair share of powerful enemies over the years, but perhaps the biggest battle that the mighty warrior has ever taken part in is the internal conflict caused by his own Saiyan pride and his unquenchable thirst for combat. Despite knowing full well that his foes could wipe out millions of lives at a moment's notice, he, like Vegeta, can often be seen toying with his enemies. There are plenty of other examples of Goku playing the villain in Dragon Ball too, including his regular mistreatment of his friends and family and his selfish antics when it comes to the safety of both himself and the planet.
12 He Toyed With Frieza
Following his transformation into a Super Saiyan, Goku has more than enough firepower in his locker to deal with Frieza. Due to his own hubris, however, he instead decides to allow Frieza the time to fully power up, and this sets about a catastrophic chain of events.
Even after powering up, Frieza is no match for Goku and yet the Saiyan continues to delay ending the battle. Upon realizing that he cannot win, Frieza unleashes a devastating energy blast that ultimately destroys the entire planet, leaving the Namekians without a home. Even then, Goku still gives him the means to survive the blast.
11 He Stayed In Space After Namek
Sometime after the destruction of Namek, Goku's friends and family gather around the Dragon Balls ready to bring Earth's protector back to life. To their surprise, however, Porunga informs them that Goku isn't actually dead, which, of course, the Saiyan had neglected to mention himself.
Buoyed by the good news, Dende uses the last wish to teleport Goku back to earth. Goku refuses to return to earth though; instead opting to hang out in space rather with his family and loved ones. This almost backfires spectacularly when the newly rebuilt Frieza and his father arrive on Earth a short while later. Were it not for a time-traveling Trunks who just happens to become a Super Saiyan, things could have gotten pretty bad in Goku's absence.
10 He Didn't Take His Heart Medicine
Interestingly, the reason that Future Trunks ventures back to Goku's timeline in the first place wasn't actually to deal with Frieza and King Cold. Instead, he did so to warn Goku about the impending arrival of some killer androids to give Goku and his friends a chance to prepare. This is because in Trunks' reality, those androids wipe out all of the Z Fighters save for Trunks and Goku, though that's not to say that the latter survived. Far from it, in fact.
In Trunks' reality, Goku dies from a rare heart virus before the Androids even arrive on the scene. Despite Trunks warning him about this illness and providing him with the medicine needed to survive it, however, Goku somehow forgets to take it, which very nearly kills him. While he recuperates, his friends are left to fend for themselves against these new bionic threats, with Vegeta, in particular, very lucky to survive. Given that he's by far the strongest of the Z Fighters and the lengths that Future Trunks went to in order to warn him, Goku's failure to monitor his illness was irresponsible at best.
9 He Pushed Gohan Into The Ring With Cell
There's perhaps an argument to be made that Goku's family was actually better off without him. For years, Chi Chi had been begging Goku not to involve Gohan in dangerous situations. Despite this though, he repeatedly goes against his wife's wishes by regularly placing their young son in harm's way for no good reason.
After returning from space, Goku picked up right where he left off, dragging Gohan into the Hyperbolic Time Chamber and aging him by a whole year in the process. After the pair emerge from the chamber, Goku pushes Gohan into the ring with the murderous Cell, who, by the way, Goku could have dealt with much earlier had he not allowed the villain to fully heal by giving him a Senzu Bean. Gohan does eventually emerge victorious, but he's almost killed in the process.
8 He Stayed Dead After Being Blown Up By Cell
Goku's decision not to finish Cell off himself once again backfired spectacularly; leading to his own death and the complete destruction of King Kai's home planet. Goku wasn't the only casualty here either, with King Kai, Gregory, and Bubbles also paying the price for the Saiyan's foolishness.
Despite his carelessness again costing them dearly, his friends are once again willing to wish him back to life with the power of the Dragon Balls. As was the case a few years earlier though, Goku refuses. Apparently, he would rather explore the Other World with King Kai than be there for the birth of his second son. He does eventually return once Goten is seven, but promptly leaves again to train with Uub once the Majin Buu saga is over.
7 He Fought With Majin Vegeta
When the Supreme Kai turns up with a warning that the greatest power in the universe will soon be arriving on Earth, most people would probably be a little concerned. Goku seems more interested in fighting and once again proving that he's the very best, however, even when he knows that doing so will further increase the chances of this terrible enemy, Majin Buu, from being released.
Granted, it's Vegeta who allows himself to be consumed by Babidi in order to increase his chances of finally defeating Goku, though this could arguably be forgiven. Vegeta's decision was driven by an inferiority complex and intense feelings of inadequacy that were born from his repeated failures to surpass his long-time rival over the years. By comparison, Goku could and should have been the bigger man, but instead agrees to fight Vegeta despite knowing the potential consequences. Naturally, billions of people die soon after.
6 He Toyed With Majin Buu
After transforming into his Super Saiyan 3 form, Goku could have easily defeated Majin Buu had he so wished. At least that's what he tells Piccolo a short while later, anyway. Instead, he holds back because he wants to see if Trunks and Goten have what it takes; once again needlessly putting one of his children in harm's way. The situation takes a dramatic turn for the worse as a result of this, which comes as a surprise to nobody but perhaps Goku himself.
Majin Buu goes on to eat or kill most of the people on earth including pretty much all of Goku's friends and family. It's also worth noting that the only reason that Majin Buu was around in the first place was that Goku had earlier chosen to do battle with Majin Vegeta despite knowing full well that doing so would lead to the awakening of the most destructive force in the universe.
5 He Tried To Pimp Out Videl And Bulma
Things get a little desperate during the Majin Buu saga and, as they say, desperate times call for desperate measures. Most people, however, would probably draw the line at pimping out their son's girlfriend and friend's wife to a lecherous old Kai. Goku is not "most people" though.
This isn't the only time that he shows a complete lack of respect for women either. In the original Dragon Ball anime, he touches Bulma inappropriately while she sleeps and even begins to take off her clothes. Not long after, he does something similar to Chi Chi, although this backfires somewhat as it ultimately leads to a marriage that Goku seemingly wants very little to do with.
4 He Picked A Fight With Beerus
Almost 15 years on from the car crash that was Dragon Ball GT, the series returned with Dragon Ball Super; much to the delight of many series fans. Unfortunately, however, Goku's judgment didn't improve one bit during his time out of the spotlight, as evidenced by his decision to challenge a God of Destruction.
The name itself should have been more than enough to deter Goku from picking a fight with Beerus, but he also received several warnings not to do so as well. Not to be deterred by a silly thing like reason though, Goku challenges Beerus anyway; putting the entire planet at risk as a result.
3 He Toyed With Frieza... Again
Given how great Frieza is as a villain, his return in the second Dragon Ball Super movie came as little surprise to anyone. Nor, for that matter, did his shiny new golden form. What was a little shocking, however, was that Goku still hadn't learned his lesson about playing with his foes.
His decision not to deal with the villain quickly once again led to the total destruction of a planet. On this occasion though, that planet was Earth. In just a matter of seconds, everyone that Goku knows and loves was obliterated due to the Saiyan's naivety. Thankfully, Whis is on hand to rewind time, but there's no way that Goku could have known that he was going to do so.
2 He Actually Became The Villain
While Captain Ginyu may have temporarily stolen Goku's body, he does very little damage when compared to Goku Black. Of course, it was Zamasu committing the atrocities rather than the Saiyan himself, but there's an argument to be made that the latter is just as responsible. The only reason that Zamasu embarks upon his deadly rampage in the first place is that he believes that mortals should not be in possession of god-like powers. His actions are certainly extreme, but there may be some logic behind his motives.
Vegeta. Frieza. Cell. Buu. All of the major threats in the series come about due to Goku and his power. The Saiyan even recognizes this himself in Dragon Ball Z, but makes very little effort to actually do anything about it. He also disrespects Zamasu in an alternate timeline by demanding to fight him, arguably proving that the North Kai was right about mortals all along.
1 He Inspired The Tournament Of Power
Having only just received multiple warnings about the potential dangers of interacting with the Gods, Goku twice more puts his foot in his mouth. First, he suggests the Tournament of Power to the Omni-King and then later reminds him about it despite Beerus telling him not to. The resulting tournament could have potentially led to the eradication of eight of the twelve universes.
Once the tournament gets underway, the other seven universes are furious with Goku, and rightfully so. This leads to them targeting the fighters from universe seven, which greatly increases the chances of Goku's loved ones being wiped from existence. Thankfully, he stumbles onto the power of Ultra Instinct and Frieza decides to play nice, but this is more a case of dumb luck than anything else.