By becoming a follower of the evil Wizard, Vegeta received a power boost that saw the return of the Saiyan's ruthless nature ...

with Vegeta proceeding to fight Babidi himself. Defeating the evil wizard effectively prevents Majin Buu from emerging from his prison and continuing the branching path, with the Z-Fighters ...

If it wasn't for the villain's evil nature and his power over the Saiyan race, Vegeta would have had an entirely different character arc, perhaps even one where he would never have met Goku at all.