People are pretty malleable though, is the thing. We like to think otherwise because it’s cognitively simple to think people (and ourselves) are static objects as identities that don’t change over time. In fact, people are very dynamic and change dramatically over time in response to their environment, self-inflicted or not. It can be anything from sudden trauma causing drastic personality changes, puberty, or rigorous work at changing one’s maladaptive thinking patterns.