Personally I find it much harder to be a player than to be a GM.

I've always found GMing to be pretty easy. You have a whole cast of characters and world to play with and if something goes wrong with that it very easy to hide it/change it for next time. Messing up as a GM(in game) rarely has permanent consequences and if you are willing to be honest you can even just walk stuff back.

As a player you don't really have that freedom. Everything you do comes filtered through the lens of this one character and you don't really have the ability to easily change that. If I introduce a bad character as a gm, they can just never show up again. If I misroleplay my PC, that sticks.

That being said by far the hardest part of any game is out of game table management, but I reject the assumption that that falls under the GMs purview.