Do you have any suggestions for an effective way to bring them down?

Perhaps building alternatives that can replace them on run in parallel is the best way to do that?

My approach for bringing them down is working on better systems/UX than what the closed-silos currently offer...And we have a long way to go.

But...Nostr (and other decentralised social media protocols) can offer things the existing platforms can not do: interoperability.

Imagine the people you follow to be the same from FB, to strava, to spotify... Imagine the content (signed notes) you make are available on different clients/platforms

That UX, perhaps for use-cases and projects we can't imagine today will be so much better than what we have today. I've tasted a little bit of just that switching between my Nostr twitter-like client (Primal/Yakihonne) and the Podcast app (foundtain.fm). It blew my mind.

This opens use cases the existing platforms can only dream about.

Pushing for strict regulation that forces them to have disclaimers like cigarettes, and treating them officially like the public health disaster they are. The free market, despite what the capitalistic religion leads you to think, is still not the only option.