But if many people think you are being petty/bonkers/anti-something-they-care-about based on why you are boycotting particular businesses, that might cause you some trouble.

> Or is boycotting not petty only when your tribe does it?

There are certainly some boycotts I don't participate in, but respect the decision of those who do.

Boycotting is petty when people think it's petty (pettiness is an opinion, not an intrinsic property of something). If you want to talk about "tribes", sure, maybe a particular "tribe" thinks some particular boycott is petty. That's life.