I think you hit on it in your last paragraph. There is no one "master programmer" and, despite job postings to the contrary, no one is an expert in the "full st

I think you hit on it in your last paragraph. There is no one "master programmer" and, despite job postings to the contrary, no one is an expert in the "full stack." After 25 years at this, I'd say get good at the parts you are naturally interested in. Are you attracted to UI? Does big data get you excited? What part of the enormous spectrum of CS really resonates with you? Become an expert in that.