Rough estimates seem to be about 100M Premium users out of 2.49B total.
Roughly 4%?
So ~96% of YouTube users are unwilling to pay for the service to avoid the ad model.
A percentage of those (I found about 11% - or more than double the number of Premium subscribers - lol) aren't even willing to deal with the ads on to pay for their use. They just want to pay nothing.
Maybe I'm missing something, but I don't see #Nostr replacing YouTube without using the same models *today* in the current culture. The best case I see would be an ad model that's more transparent.