They're trying to get laid, looking for every advantage possible, it's a slippery slope though. I had a buddy in college try to get me into "The Game", but I never had the stomach for it, just seems disrespectful. On the other hand, I've been single for longer than I care to admit, so...
Honestly it's mostly a matter of not being a dick and trying to meets lots of new people (primarily as friends, but being open to other things). There's plenty of horny people around.
The way I see it the biggest thing people struggle with is the meeting new people part. And also, personally, I'd avoid stuff like dating apps. Try to go to hobby meetups and such instead.