Why Azriel isn't a doctor

There's so much to consider when writing an immortal character that ages slowly, with Azriel he lived through about a century at this point- to the point where in this world people evolved from using horse carriages to driving cars.

I think to myself what is something he would and wouldn't try- I want to give him medical knowlege to an extent but his main hobby is just reading because he doesn't like interacting with others.

I could see him be a surgery in a parallel dimension though- one with terrible humor.