Complicity is only with those willfully ignorant, I imagine. Colonialism ~is~ a malevolent mass. "Rich white persons" tend to be the force behind colonialism, but theoretically it could be anyone.
People can migrate without being colonists. Certainly a lot of historical migration was due to colonialism, but someone who moved to a developed country last year (from either a developed or undeveloped country) clearly isn't guilty of it.
Second, even if the parent commenter's ancestors were colonists of some stripe, people aren't bound in any way to say that the actions taken by their ancestors were the right ones.
I'm not pretending to claim some sort of native ancestry, and being the result of colonialism doesn't preclude me from disapproving of policies and interests beyond my control.