In our society there's this huge pressure to achieve I'm sure we've all felt it and there can be a lot of confusion between approval and love and worthiness so self-worth can become contingent on achieving rather than just unconditional. We would be more genetically predisposed or evolutionary predisposed to excessive confidence instead but then we also have species filled with narcissus which is in itself saying as a disorder so imposter syndrome is not a disorder but narcissism definitely is. There seems to be some adaptive benefit to humility and perhaps a tiny bit of self-doubt but also adaptive benefit to confidence as well.