Until proven otherwise I'm defaulting to the Abridged take on this one as canon.
(But also, there's zero surprises about a royal with no known job or active political role to marry a rich heiress. If anything, Bulma's absolutely atrocious taste in guys is what needs some explanation)
There's a scene in DBZ Super where Vegeta states that Saiyan men are inherently attracted to strong women which is why he and Goku are so content with their wives.
I also recall that at one point Vegeta said that he saw how fighting for family and friends made Goku stronger and he wanted to see if it worked for him, too. I can't remember where tho. But on the other hand on the Majin Buu arc, he said he just fell into the role.
Funny, in DBZ Super (as much as I saw) Vegeta was practically the good guy, fighting to protect his family and world and it was Goku who threatened everything with his selfishness and lack of care.
His species, family, coworkers, and friends all died and he had nowhere else to go. He banged a hot chick and liked it enough to put up with wearing pink shirts to keep doing it.