I think most people stay subscribed just to watch them play games they like or are interested in, or at least that’s the only reason I can come up with.
I think the biggest downfall for the Game Grumps channel is the sheer amount of videos they put out. It’s three videos per day, I think, usually about 15 minutes or longer for oneshots or big games. Uploading to Youtube daily causes burnout fast. I’m not sure what their schedule is like now but I remember sometimes Jon and Arin would start filming around noon and wouldn’t stop until 9 am the next day. Most of the popular channels you see now record batches of gameplay every few days, and then cut out any uninteresting parts to make a good 20-30 minute video, and those do great. GG hasn’t and won’t update their formula, so instead their subscribers get 100+ episodes of the same clips of Arin running in circles and yelling about the game being terrible since he didn’t read where to go. He’s the child who wishes they could play video games for a living and now that he actually does that he fucking hates it.
I really tried to hang on to Game Grumps for a while, hoping it’d get better, but I finally let it go when they played Super Mario Maker. Every episode was Arin playing levels with less than 10% pass rates, taking five steps, and screeching when he died. It never gets funny. You can hear in his voice how much he’s faking his rage for views and it’s infuriating. That old clip of him blowing up at Sonic 06 got incredibly popular and it’s easy to tell he’s still trying to ride on it, thinking yelling earns views.
Honestly at this point I’m just waiting for Arin to piss off the right person and have all the truth come flowing.