I'm coming up on about 4k hours now, granted I have been playing since August of 2016. That's still a huge chunk of my life spent on such a simple game, Garry's Mod has unlimited potential so long as you know how to work your way through the workshop, or code your own addons. There's a plethora of Gamemodes that you can choose from at any moment, new ones popping up every hour, day, etc. Garry's Mod was well worth the $10 I spent on it a few years back.