They could ask the users to pay for the content they produce and measure how many microseconds would pass before they switch to someone else's videos.
It's an option.
I don't want to watch ads, I skip sponsored sections, I feel no guilt about it, if they can't monetize enough and have to shutdown operations, I can survive without that content.
What would you say if I was dancing in the middle of the streets asking for money and blaming people who don't give any because "I am not being paid for the show I've put up, you ingrates!"?
Nobody asked or forced content creators to upload their content on YT.