I grew up Catholic, and (at least here, Catholicism is a really big place) it's not so much "he has money" as it is "he will bring stability."

The second commenter's "cash cow" comment is a bit of an outlier in my experience, because usually the highlights of dating a nerd are more akin to the second comment. They'll be an active father and attentive husband, and they're less likely to cheat (in their view). I've also heard things like this about D&D/Warhammer players, because they use their imagination alot (making them good at entertaining children) and the hobbies take a lot of focus (meaning they'll be willing and able to tackle problems that arise).

Older catholics are used to men whose only role in the family is "produce baby and produce money", so a lot of modern dating advice is in the guise of "make sure he's a good man before you marry him"