What does your comment have to do with OP's boss being willing to give him responsibilities beyond just being a coder - despite being rude?

OP's position is:

"I'm valuable, just ask my boss. He sings praises for me"

It is a very naive position that needs to be eradicated If it is not, then "take 50% off your salary and be happy about it" would be a norm. In our society money and power are proxy for the value.

People get promoted to one level above their competency because at the top level of their performance they do well which means that they are promoted one layer higher. That's the last promotion they get.

I always found the Peter Principal very interesting even if not entirely compelling.

https://en.m.wikipedia.org/wiki/Peter_principle