Has it ever occurred to you that game developers need money too?
RiliSoft has only ever made 3 games, all of which are free apps, all of which have in-app purchases. Why you might ask? So that people can give money to the developers so they can pay for a variety of fees (rent, utilities, server maintenance, etc.) Some people do freeware games on their own time, yes, but RiliSoft actually has a building that runs all of their servers, has their computers to code the game, and might even have a small lounge. In short, it takes money to even run these sorts of games.
The next time you say it's "Pay-2-Win", think of this. I've known several people who can still kick butt in a server, with nothing but a Pixel Gun and Simple Shotgun. The game is balanced, though with the new upgrades it's become chaotic, it is still possible for a casual player to play a round and get some kills in (and maybe a win too).