In addition to the many other fine comments here, I will add that when you think someone is so stupid there is often something missing. You may not understand what information they are acting on or you might be interpreting the context according to different values than theirs. As an observer, not understanding someone else’s choice can feel exactly like “damn what a stupid choice.” I try as much as I can to take these as opportunities to dig further and use my imagination to figure out what they must be thinking. Occasionally I come up with something.