It's a bit perplexing, but it's one phenomenal character that has caught fire like nobody else. The right combination of elements and it's appealed to millions. It doesn't have to make sense, but it's not difficult to comprehend how one guy can trigger such a following.
On the other hand, there's Minecraft machinima. Channels and channels and channels of Minecraft machinima, and they all have multi-million sub counts and zillions of views. It's not just one successful guy doing it, everyone is doing it and many channels have built empires out of it. I...how the?