There are 20 other reasons to be 'weary' of living in SF that are just easier to grasp, like 'rent'. Also - maybe I'm wrong but when I lived there it felt like 3 guys to every girl. At least the way social networks work because they are so tech-focused.
But materialism is what it is ... so yes, you'll get some negative aspects from having clusters of money.
The Battery, MaiTai, and other private clubs facilitate such encounters.
Having been to cougar nights at The Rosewood I have a bit of an idea on how it ends and it's not pretty :(
In Latin Europe and South America it's quite common.
Not so much in US. Not even really in SF as much as Spain or Italy.
I hope this doesn't mean that you aspire to one day be the guy that girlfriends leave their boyfriends for.