I mean, there are some people you'd prefer to befriend/date/marry over others, right?. your criteria is probably not just money; you might care about physical characteristics, intelligence, character, etc. to the extent your criteria overlaps with others', something like a market emerges, though the prices are not denominated in dollars. "value" is kind of a crude word to use, but it's a useful abstraction to answer the question of why some people have very many options in friends/partners and some have very few.
That's the whole problem, right?
I just want everybody everywhere to occasionally step back and consider how that is the "why" of all of this; our society is set up, or has evolved (devolved?) into this place where people must consistently ensure a steady supply or source of money for mere survival, and from that is where the generally natural thing of sex and how it works among the genders et al creates these imbalances which can be converted into money. It's hard to understate how deep this goes; e.g. marriage et al.