Not sure it’s rational of itself. It may be rational for you if it maximizes your wellbeing over time, but not for someone who would be thoroughly depressed if they adopted that belief.
My own view is that it is useful to develop a capacity to not put people in a ‘good’ or ‘bad’ camp until you have sufficiently strong evidence (and even then retain a sense of nuance), but instead maintain a ‘neutral’ category. There are more than 7 billion people in the world that I don’t know. Should I be inherently suspicious of them all, or believe they all have my own best interests at heart? Well, neither. As I get to know (about) them, I adjust my belief in a Bayesian manner, in either direction.
By some weird coincidence, today’s post is kind of about that!