I've said it before and I've said it again: ad-based content and pay content are incompatible business models. YouTube Premium fails because the content isn't worth paying for. The content is not worth paying for because it's been designed from the ground up to sell ads.
When a website designed to sell ads fails to sell content, that's not evidence that selling content doesn't work, it's evidence that selling content designed to sell ads doesn't work.
When a website designed to sell ads fails to sell content, that's not evidence that selling content doesn't work, it's evidence that selling content designed to sell ads doesn't work.