Let’s not forget the unmentioned income thanks to gathering all that user data.

The real value of Youtube (and social medias in general) is not the raw revenue they generate.

It’s being able to be able to predict what will trend in advance. Which is proven by their 200+ billions in revenue from ads in general.

It’s extremely likely that in an alternate universe where Google doesn’t own YouTube, their profit today is lower than what they currently have.

But like you said, poor YouTube is not making money explicitly on its own so they’ll use it to justify any cost increase attempt when they already know what the real money maker is.