I agree that in the vast majority of cases trying to prove things, people pleasing and placing your value based on others' opinions is unhealthy and toxic.

But personally (half jokingly, half seriously) the amount of satisfaction I get from proving people wrong outweights all the frustration and unhappiness.

That could just be me being a spiteful little gremlin but that is something that not only motivates me but makes me happy. It also sometimes calls out to my sense of justice.

I had a terrible friend once who would always put me down (usually disguised as "being honest" or backhanded compliments). So I thought, you know what, I'm not doing that anymore. And I made it my goal to come out on top. Now our situations completely switched. I'm in a happy, healthy relationship, studying something I like and I'm good at, my family life is much better and my finacial situation though not great isn't bad and I know that is completely due to my own efforts. And of course I didn't do all of that just to get back at that person. But that was definitely a factor that motivated me to get to the happy place I'm at right now.