I think you are selling his character too short. In the middle of Goku's fight in the Cell Games, Vegeta flat out stated that Goku and Perfect Cell were stronger than him, yet was the 1st person to challenge Super Perfect Cell (and didn't seem to have any belief that he was stronger than Cell). He also flat-out told Krillin that the Giynu Force was stronger than he was when he heard that they were coming to Namek, yet still made plans to fight them instead to trying to leave the planet. And outside of Movie 8 (and even there he got over his fear), none of the other 13 Z movies has him punk out against the main villain despite their obviously superior power. And if Vegeta wasn't interested in challenging himself throughout Z, why did he continue to train after the Cell Games despite Goku being thought to have died for good and Vegeta becoming the strongest character alive before Buu is resurrected?Kunzait_83 wrote: snip
And I don't recall Nappa having a mental breakdown or bitching out when he heard that Goku had a higher power level than he does ("what, over 8000? lol). Instead he rushed off to fight Goku despite the clear knowledge through their scouters that Goku is stronger than him.
And then there's 90s Bardock, who was frequently facing off against foes stronger than himself and was never necessarily portrayed as being exceptional among the Saiyans for doing so in the film.