> What’s in the collective best interest may not match with what’s in the individual best interest.

The alternative isn't what is in your best interest, but what is in your boss's best interest

The mutual interest of me + 'my boss' might very well outweight my fraction of the collective interest. It certainly depends.

Also, if you are in ESOP that might change the equation as well.

that's certainly one alternative, but can we stop looking at everything as a bipartisan scenario with binary outcomes? Maybe there's lots of aspects with mutually aligned interests? Perhaps every single thing in life is not a "us" vs. "them"?

Sure, that's exactly what a union is for.