I mean, they provide the service by stealing data from their users. I would argue that this is just as ethically fine as Youtube's entire business model.

... if there'd be a healthy amount of alternatives/competitors to chose from, that would probably be true.

However, as we all know, it's basically a monopoly.

Absolutely! When you discount for cable tv, satellite tv, airborne tv, Netflix, Amazon, HBO, Disney and others.

Because we are hackers and everything we don't like (or don't want to pay for) is automatically a "monopoly".