Because we are sick.
I grew up in an Abusive, Alcoholic home....
I learned from a young age that I was not good enough, that I was not pretty enough and not smart enough. I was just never enough. I married and Alcoholic and then I was not a good enough wife or Mother....etc.
When you really honestly believe you are not enough and never will be ... you settle for what comes to you. Because of my thoughts as a younger person I married because he asked and did not think about if he was good enough for me... I would not apply for better jobs because of the fear I was not smart enough and did not want to be embarrased again... I would accept attention from men that scared and abused me because I was not pretty enough...
Self Sabotage.