MrNoC, I don't have the time to read what's in your other 56 posts, but tell me they are not all probing questions like this one? If you're just curious, or just finding this a way to generate a little sexual tension and spice up your mental life - no problem. Interesting question, actually.
If you're an academic or researching a serious book - cool.
If you're a local news reporter working on a prostitution angle for the upcoming sweeps. Fuck you.
If you're a law enforcement officer - this is all in fun, sir.
Assuming it's the first of those possibilities, the reasons a young man might choose to purchase sex short-term are sort of obvious, aren't they. I know you said you enjoy the chase and capture, but surely you can imagine men who don't. Not too many men may come on here and say, "Women make me nervous but I still want sex," but you know it is common.
As noted above, some guys are very busy pursuing their professional development. We may debate whether they are wise to live such focused lives, but they still want sex, and some companionship if it doesn't require distraction from the normal course of their interests.
Between girlfriends is going to be common. A lot of so-called civie relationships come to an end and guys who were getting good sex don't want to go cold-turkey. Purchasing sex is an option for them. Some may have a regular provider whom they visit between girlfriends.
Often after a relationship ends (often badly) these guys don't want to begin the hunt so soon, with all it entails. So add them to another group of men who have gone thru the bust and boom cycle often enough that they decide that the emotional wear and tear isn't worth it. So they step out of the civie circle entirely. I would imagine that most are well out of their 20's before that happens, most of the time.
The very forthright Mr Mexico (above) represents what it probably a niche market -- younger men who have made the effort to become sexual connoisseurs. On the Bell Curve of sexual interest they are down on the skinny end toward the right.
http://en.wikipedia.org/wiki/Normal_distribution They are rare, too, (I think) in that they are sharp and have the kind of confidence that often only comes with age. They know where they itch and they know where to get it scratched.
The older guys will tell ya that they do it because mamma don't give it to 'em at home, or the spark has gone and they want to find it again. It's probably true sometimes.