Not wanting to be promoted is fine, but it does come at a cost because along with that extra responsibility you may also be sacrificing influence over the thing

Not wanting to be promoted is fine, but it does come at a cost because along with that extra responsibility you may also be sacrificing influence over the things you do care about. You can still have that influence through other ways, but it takes work and may involve all the things you were trying to avoid by not getting promoted. N.B. I’m not saying that higher up ICs influence things by coming in and saying, “I am an IC6 and I think we should do it this way,” but they often have more opportunities to have the right conversations, and have hopefully learned good influencing skills along with technical skills.