If that idea of your lifetime not being enough is stressing you out, Dr David Burns' work on cognitive behavioural therapy might help. Saying you want to be an expert in many things because you are interested in many things could be papering over some deeper anxiety-driven motivations around 'not being good enough' or 'not being worthy of respect' or 'needing to prove yourself to someone' or 'not wanting to be a nobody' or 'wanting to avoid the bullying you used to get' or etc. The Feeling Good podcast[1] is a good audio introduction and has many examples, his book Feeling Great is more of a self-help style written introduction.
The important question is not "what should I work on?" or "how should I decide and prioritise?", it is something more like "I have thought processes, they model imaginary futures and guide me away from predicted harm. Why do I have an imaginary future of not being enough of an expert and feel suffering in the present? Where did that thought come from and what is it doing for me, and do I want to keep it?".
You can go with the desire for expertise part, "why do I need to be an expert in many things?" - whose respect are you trying to earn? Whose criticism are you trying to avoid? Who are you trying to avoid being like? What emotional disaster is that trying to protect you from? Or the other side, "what is so bad if I am not an expert in many things on my deathbed?", what's imagined social or emotional harm is that warning me of?
The important question is not "what should I work on?" or "how should I decide and prioritise?", it is something more like "I have thought processes, they model imaginary futures and guide me away from predicted harm. Why do I have an imaginary future of not being enough of an expert and feel suffering in the present? Where did that thought come from and what is it doing for me, and do I want to keep it?".
You can go with the desire for expertise part, "why do I need to be an expert in many things?" - whose respect are you trying to earn? Whose criticism are you trying to avoid? Who are you trying to avoid being like? What emotional disaster is that trying to protect you from? Or the other side, "what is so bad if I am not an expert in many things on my deathbed?", what's imagined social or emotional harm is that warning me of?
[1] https://feelinggood.com/list-of-feeling-good-podcasts/