Young people in general are having less sex but young men are having a noteworthy amount less than young women. And the delta between the two groups is a new thing within the last 10 years or so.
I doubt the ratio is that extreme, but if the delta exists isn't the logical conclusion that a smaller subset of the men are having sex with a larger percentage of the women?
A quick stab in the dark is a sugar daddy, older man, more established with more free disposable income. My only evidence to back this up is anecdotal, I have young parents. I am 28 and my dad is 46. Parents divorced a few years ago. My Dad works sales and makes a good chunk of money. He recently stopped going to bars because all the 20-some year old girls would hit on him and get a little too close for his comfort, which grosses him out because my sister is 26.
Edit: I found it funny when he was complaining to me about it because all I could thing of is that these girls probably don't know they are hitting on a guy with grandkids.