Black markets are usually the result of failed markets, and i think its no different here. Copyright is a monopoly so there is no competition. Sure different streaming services compete with each other, but they essentially sell different products. It'd be like if only one resturant was allowed to sell hamburgers. There might be other resturants but they arent really in direct competition.

The streaming services are relying on enforcement to preserve their business model.

This only works as long as there's no other nations with significant digital infrastructure that can be used for VPN egress points who don't care a whole lot about US copyright enforcement (or copyright enforcement in general).

Our government just pissed off a lot of other governments. Enforcement is good within the US, but not outside, even nations which the US has a lot of control over.