The sacrifice of Majin Vegeta is thought by many fans to be the character’s best and most defining moment in the Dragon Ball series. His constant bouts with Goku and struggle with finding a place for himself on Earth all appeared to reach a resounding conclusion in chapter 467, titled, “Farewell, Proud Warrior.” Though this seemed like a satisfying ending for Vegeta at the time, the entire premise upon which the scene is built is ruined by just a few details.
Prior to the battle with Majin Buu, the Supreme Kai had made his presence known to the Z Warriors and used Gohan as bait to lure Babidi’s minions out. By following them back to Babidi’s spaceship, Goku, Vegeta, and Gohan began a series of trials in order to descend further into the evil sorcerer's spaceship. During these trials, Vegeta became increasingly irritated at Gohan’s weakness and the speed at which they were making progress through the battles. It was clear that Vegeta was only tagging along so he could make sure he’d get his fight with Goku. Babidi’s minion, Dabura picked up on this divide between the Saiyans and informed Babidi that Vegeta would be a good candidate to use mind control on because of the apparent evil within his heart.
The reason why Majin Vegeta’s retribution is a failure is simply that, at the point of his sacrifice, Vegeta is pretty much irredeemable. Akira Toriyama makes it a point to demonstrate that even though Babidi has latched onto the evil within Vegeta’s heart, Vegeta is still in control. Vegeta is resisting Babidi’s orders throughout the entire ordeal and kills innocent people when acting of his own volition. The blast he fires into the stadium of the World Martial Arts Tournament almost hits Bulma as well, coming just meters away from killing her. The fact that Vegeta is the one behind this abhorrent violence and not Babidi is what ruins Vegeta's redemption. Vegeta's resistance to Babidi's mind control should be what spurs him into regret, not what allows him to mindlessly kill.
This wasn’t the first time Vegeta almost doomed the entire Earth either. In the Cell arc, Vegeta is solely responsible for the events that lead to Cell achieving his Perfect Form. Vegeta’s pride and arrogance led to the death of both Goku and his son, Trunks. It was already out of character for every Z Warrior to automatically be comfortable with Vegeta living on Earth past the Frieza arc, but once Vegeta proves to be a problem, he should automatically be exiled or dealt with. There is no reason to have any trust left in Vegeta after he betrays the Z Warriors for the third time and puts the lives of everyone on Earth at risk.
Vegeta’s actions have time and time again led Dragon Ball’s Earth down a darker path. Pride and arrogance are key parts of his character but there is only so much one should be able to sympathize with. The components for an amazing character arc were all there in the Majin Buu arc, but because Vegeta is the one still willing enough to nearly commit genocide just to fulfill his selfish desire to fight Goku. There is also no real moment of clarity for Vegeta in his battle against Goku, he just randomly decides he’s had enough fighting. Trunks and Bulma aren’t even involved in his decision to stop fighting when they could have been key components to his decision to overcome the latent evil within him. Despite coming close to a fulfilling character arc, Vegeta’s development during Dragon Ball's Majin Buu arc is stunted by his own greed and penchant for violence.