web development – Is it possible to be a self-taught AI dev, and is physics necessary?

So I’m learning (self-taught) web development , and I want to get a job. I have a vision that first I learn web dev, and after I’m decent at it I will start learning machine learning and AI and study maths. Is it possible to be a self-taught ML or AI dev?

Do AI/ML devs earn more?

Then my last question is whether I need physics in web dev or AI or is it unnecessary to learn?