Why do we tear ourselves apart?

Something I've been thinking about is.... Why do we as humans tear ourselves apart? We're never happy with how we look. Our results in school or tests. We never feel satisfied with how we perform, we could always do better, be better, look better.

I guess in the sense of evolution and those best or best adapted will survive. I.e if you look best you're more likely to get a partner and to keep your own dna going. If you're the fastest you are more likely to get the food.  If you're the strongest you're more likely to win at physical fights. If you're the smartest you are most likely to survive and figure ways out or find new ways to survive and adapt etc etc

So maybe it's just a built in thing,  that we always look down on ourselves, always make ourselves improve and feel worthless if we're not the best. Because in a sense if you just accept your average or lowest "best" then yiu aren't really growing and progressing. And society wouldn't really progress either if everyone just accepted things and never decided to be the best. ... Because unfortunately there will always be someone who is the "best". But that doesn't mean you are worthless or need to feel bad. We need to learn to be happy with ourselves, always. See our progress,  fight for progress but still be happy with where we are at the moment and who we are. Because the fact is going from A to B, going from having an F in maths to having a C in maths. Or going from over weight ti normal weight, it takes time. It's not something that happens over night and so you need to accept that and be happy with yourself that you are trying, that is the most important.  And stop tearing yourself apart for your appearance.  You are who you are and everyone looks different, but you need to accept and love yourself for who you are. It's ok to want to progress or change, I mean the body is capable of change but at the same time that takes time and if you always hate yourself you won't be happy.

We don't need to tear ourselves apart because in the end you will be completely torn apart and can't put yourself back together. You need to be kinder to yourseld.  Stop thinking that you're  useless and worthless,because you're not. Don't let your mind bully you and  tear yourself apart. Be stronger than that and dare to love yourself.  Dare to love yourself no matter what stage of life you are in.  No matter if you want to progress and change,  love yourself now and stop thinking that you are useless if you aren't where you want to be.

Be proud over yourself.