They are what they are and that is that. They have anger issues, or they’re insecure, or they’re not very good at something. That’s how it’s always been and in their minds that’s how it’s going to stay.
Sometimes, it’s because they don’t understand the difference between a fixed mindset and a growth mindset. As Carol Dweck points out, someone with a fixed mindset believes that their abilities are set in stone, inherited, immune to change. On the contrary, someone with a growth mindset believes (rightly) that their abilities and character is capable of adapting and evolving.
Or maybe they do understand this, but it’s just easier to persist as they are. Maybe it’s easier to stay the same, to have the same faults and do nothing about them. Maybe it’s easier to accept your flaws and bemoan them than it is to accept and decide to remove them.
Maybe they’re just lazy. Maybe they’re scared. Perhaps they accept the impermanence of their habits and behaviour but are overwhelmed by the task of improving them. They see all the advice, all the gurus, all the available sources and have no idea where to start.
Or perhaps it’s not ignorance or laziness that drives their lack of motion, but fear. They know they must change but they’re scared. They’re uncertain. They need a guiding hand.
Or another possibility: they understand that they can choose what to become, they recognise that they have the power to determine who they are, but to do it in every area of their life is too exhausting. So one may strive relentlessly in their professional life, but make no effort to improve their social life. Or perhaps they put the bulk of their efforts into being the greatest parent ever and are willing to let their career suffer as a consequence of that choice.
Whichever cocktail of the above reasons it is, it still remains a sad truth. Some people are not interested, don’t know, or just straight up don’t care about improving themselves.