Throughout Dragon Ball Z, the Saiyan prince is defined by relentless ambition whenever an opportunity to increase his strength arises. Even by the time of Dragon Ball Super, when he’d embraced the role of a hero, Vegeta’s obsession with victory was still his main motivation. His greatest quote from Dragon Ball Z perfectly both demonstrates that mindset and highlights why it makes Vegeta so iconic. As Dragon Ball Z progresses, Vegeta also begins confronting the psychological scars left by Frieza's destruction of Planet Vegeta. Viewed in hindsight, "My heart is pure - pure evil" represents the perfect midpoint of that evolution.