That’s because he aims at a very specific hyper engaged demographic. The pre-pubescent teenager. Then they keep watching either out of habit or emotional stunting. They might not be a very sofisticated audience, but they are very dedicated. It might be all they watch, they construct their identity around the content they watch and demand parents to spend money on the products pushed to them by their favorite influencers.
This is not unusual, all generations have done it and diverse agents have capitalized from it. From boy bands, to star wars, Disney kids/adults… They are the unicorn audience in marketing, if you can get your claws on a person during that development stage, you got yourself a consumer of your brand for life.