I 'like' talking and thinking negatively about myself

Sometimes it actually feels 'good' to call myself a loser. Or that I just suck at things. I know I shouldn't do this, because it's detrimental to my mental health. But often it's easier and it feels 'better' than saying something positive about myself. The negative feelings much better, more and freely than those positive things I actually need to enforce upon myself.

Whenever I try to think positively, or did something well, it's taken for granted. Do I like to punish myself in a weird satisfying way? Or am I still deeply traumatized by past events?

This can't be healthy.