It's hard and it's usually slow growth, but people can "blow up" over the course of a few months if they post videos on the right topics/games. It's not always years but you have to post the right stuff. I think you can put yourself in a position to blow up by doing research and experimenting.
There's a lot you don't have control over yes, but if you keep trying different things you give yourself more chances for it to happen. You also get information on where there is/isn't demand for your videos. There are niches/markets with openings for new channels right now, it's just a matter of finding exactly what that niche is and how to work that into what you enjoy making videos on.