Also, The only people who could do this are already making tons of money. We're talking about people with high technical skills, not the people posting ASMR videos.
You also need to attract viewers to your platform, which is no small feat.
Of course, this gets at another reason why owning your own platform doesn’t make sense, which is that web infrastructure is a specialty that most people have no interest in, and if they did, probably limited innate ability and training.
If it were that easy for people to suddenly pivot into a 6 figure salary field...more people would.
I suspect such an industry does exist, but it's quite a bit smaller than both the number of people profitably creating content on YouTube and the number of employees of YouTube itself, which tells me that maybe the risk-adjusted returns of it aren't as great as you think.