I can think only for one legitimate reason:

• Google bought out YouTube and operated it at loss for most of its life, effectively making it a monopoly in the process, and only started to earn money on it when there was no way any other alternative would come up and endanger it.

If you ignore this, YouTube Premium is a pretty good offer. And I personally like the fact that I support content creators, without the need of watching ads that are nothing more than cancer for society.

That said, I would still prefer YouTube to return to its roots and separate from Google, since it's pretty much possible for it to stand on its own right now, I guess.