Thanks Dien.
I have a slightly different view.
1. Brain surgeons earn more than general practitioners.
2. At the same time, most innovation lies at the intersection of 2 fields.
One awesome example is from the field of music. Look up Lindsey Stirling - the violinist. She is very famous and all her videos get a few million views on youtube.
https://www.youtube.com/watch?v=aHjpOzsQ9YI
But she is not the best violinist out there - there are a lot of violinist better skilled than her. Nor is she the best dancer. But she is the best dancing violinist.
Focus on 2 fields - not 12. Become better than average in both - but not necessary to invest 20 years to become the best in any of them. And then merge the fields and create a position for yourself.
For eg: You could mix your physics skills with copywriting and become the best person to help scientists apply for grants.