I say this from personal experience.
It doesn’t matter if your work is top notch or you bust your butt harder than anyone around you. It doesn’t matter if you have impeccable knowledge and experience, ridiculous talent, stellar credentials, or recommendations from the top singers in the world: You cannot prove yourself.
It is impossible to prove your worth. If someone does not acknowledge or recognize the value that you bring, you will never be able to convince them. It is a waste of your time, skill, and energy. They have already decided that you are beneath them and it has nothing to do with your abilities and everything to do with their need to see themselves as “over” you. And quite possibly, it is more about eliminating you as a threat.
Quit wasting your time.
Know your own worth and go live in it.