Dragon Ball is no stranger to taking villains and eventually redeeming a few of them by becoming part of the good guys. It's shown with Tienshinhan, Piccolo, and especially with Vegeta. However, Vegeta's case took not just an arc, but an entire series for his redemption to happen in the eyes of the earth. His beginnings were explicitly almost genocidal, as he threatened the planet Earth much more directly than any other villain shown at the time. Dragon Ball didn't hesitate to make the slow-burn to redemption almost difficult for Vegeta.