You have an Elo rating, like in chess (or something like that - it depends on the app and they sometimes tweak it, but the gist is that rating is defined recursively: your rating increases if you get liked by high rated people), and you get matched with people within a given range around your rating. When you lose interest they punctually entice you with out-of-range profiles.
Like in chess, they show you very high rated people at first, to ascertain your initial rating and above all to hook you with all the attractive profiles. As your rating becomes more and more accurate as people in your pool swipe you, your range of matchable profiles narrows down.
(Edit: As another user said, you may sometimes lose rating by matching low-rated or too many people, but the exact details may change a lot.)
The main target demographics are the really high rated people (who entice everyone else) and the really low rated people, who pay up for every premium feature in order to get noticed, i.e. artificially boost their rating. (But just because you have a GM's rating doesn't mean you have a GM's skill, so the gains are hollow and you have to keep paying to stay above your original rating range). The equivalent would be chess beginners paying up for an Open Tournament in order to help subsidize the GMs appearance fee and prizes.
And as in chess, an elite of very high rated people has all the fun while everyone else sorts of sucks and flounders. That's not because of evolutionary psychology or some fundamental truth of human nature, that's just how rating (and by extension any kind of skill following a power-law distribution) works.
I agree, it comically sucks that people are letting themselves being paired by a shitty implementation of League of Legends.