If they're not hacking the game, then they get good by simply playing the game all the time and practicing. If you play the same type of game all the time, then you can get pretty good at them. Like my friend for example, plays games like Dark Souls and such and he's really good at those types of games. I play platform and action games a lot and I'm pretty good at those. When you play the same game all day, every day, you're gonna get good at it.
