If you want your social media neighbourhood to resist gentrification, you could make it harder for the gentrifiers through one unique trick:
Decentralization!
Specifically by:
1. Creating accounts on small instances.
2. self-hosting your own instances.
3. Connecting with encrypted peer-to-peer messengers
4. Creating communities built on open protocols -- not platforms
Reactionaries can gentrify one space. They can't gentrify all of them!