I've seen a lot of similar scams on facebook that target older women... not really young attractive guys, but attention is attention. I'm sure there are people who fall for it. Just be thankful your friend found out this guy was still looking for some one else. (in effect, scamming/cheating on her)
Also, the scams that have people calling the elderly pretending to be family members who need money.
There are scams where they pretend to be "Windows" calling you about your computer problems.
Secret shopper scams that actually send you a check that never clears. (you are supposed to buy a money transfer of some sort... western union/
gift card with the "check")
There are people calling pretending to be the local courthouse. (number matches, and they use the correct names of judges/etc) Sure, call them back and the courthouse will tell you it's a scam. But how many people just get scared and fall for it?
Sure if you stop to think about it, or look into any of this at all, it's obvious...
But these scammers count on people falling for it because they get panicked or emotional. They prey on the desperate.
I think it's a little much to equate sensible to rich though. And rich people get scammed by hedge funds/pyramid schemes/investing scams all the time. Maybe not the ones you know, but it happens.