Power is an important aspect: reread Jung.
Carla Bruni isn't so young anymore, 40, I believe but she is very rich, as well from heritage (her father 's biggest shareholder in Pirelli) as from her modelling an singing career, yet she married that French egotistic dwarf.
Some marry old men DESPITE their age, some very rare (those girls who are unsure about themselves) are blinded by his experience of life, his "style" (whatever that is in their eyes) but most girls who marry old men have obvious $-signs in their eyes an $-ideas in their head.
Smart old men use prenuptial, smarter old men use trust funds.
Why do older men do it? Not that much for sex, but for their image, to show off to the world they're not that old and that they can get "the best", be it in clothes, cars, hotels or chicks. For those women, the feeling they're considered as "best" or "upmarket luxury" is perhaps the deciding factor.
The real gold diggers get pregnant as soon as possible and call it "love" ROTFLMAO.
Male gold diggers can't.