career

Unfortunately, I will not be able to give you right directions because at the age of 50 and almost half of my life spent in IT, I am still not expert in any area.

However, few reflections on whatever you wrote:

You will need to define for yourself what do you mean by "expert". Because there must be a benchmark to decide when you have become an expert.

You have not mentioned your current level of expertise, but if you are entering into asp.net area, you are better of looking into asp.net mvc and asp.net core. Normal asp.net will probably become extinct very very slowly, just like VB 6.0.

All you have to is keep coding. Keep attending events and conferences. Answer questions asked at forums like this. Never say "I don't know". Do Microsoft certifications. And many more....