The grown-up Vegeta as te know it might be a pain in the ass,but he only turned into that because of his child hood. Vegeta was a really sweet kid untill a tyrant named Frieza came along and screwed everything up.He took little Vegeta and made him his 'little monkey pet'.Frieza trained Vegeta and changed him.He made Vegeta's little cuore turn to stone,telling Vegeta to never trust anyone.Making the young Prince into what he is today.So don't blame Vegeta for all the things he did,blame Frieza,the one who messed up Vegeta in his childhood.