I don’t think that self esteem comes from accomplishments per se’. I think you are right that any kind of person can have low self esteem.
Self- esteem is something that mainly comes from inside – from knowing that you are Hashem’s child, that He loves you, and that you have G-d- given potential to do amazing things. And this is true no matter what traits and abilities you have. We all have the same potential in terms of Ruchnius, and it’s the Ruchnius accomplishments that should give us true self-esteem.
The problem with non-Ruchnius accomplishments is that the more one achieves, the more he feels he needs to achieve, so he is never satisfied with himself. Also non-Ruchnius accomplishments have no intrinsic value and don’t reflect on the person doing them so they can’t bring true happiness and self-esteem unless they are connected to Ruchnius accomplishments and viewed as a tool for Ruchnius accomplishments.
The best way to gain self-esteem is through working on bitachon. Reading Shaar Habitachon in Chovos Halevavos can be very helpful.
The other two important things are: 1. making sure you have a good support system and hanging out with positive people who like you and think well of you. 2. Taking care of yourself.