You can't grow niche sites that big. You certainly can't grow paid social media sites big. The mainstream social media sites work because (A) they use freemium services. (B) they aren't niche. So the answer is no you can't gain network effect that way. The model would have to be more like theirs to have any significant growth. Can you think of any blockchain projects that understand and do that is the real question.

Metcalfe's law is undeniable. Every free social media site has a great potential of gaining that. By default Metcalfe's law makes networks valuable. I can't think of anyway around that.