Its possible but with all youtubers they basically have to establish an audience and they have to hit tiers of subscriber levels. So basically it was easier to do back when. Its possible you could do it casually and if folks liked you enough you might get to the point where you get some payment and then if it continues to grow at some point you might be able to quit your day job. As you said its a crowded field though and all the established folks will show up higher in searches for games.