Someone who only picks up skills and knowledge that are directly related to his/her field of expertise and ignore other fields, risks having too narrow a perspective; is a narrow technologist and a bad thinker.
In the long run, the one who over-specialises might be worst off in his/her field of expertise than his/her colleague who simultaneously has wide interests.
From my personal experience, many things are interconnected, and one can almost always apply knowledge or wisdom derived in one area of life to another, or identify similar patterns between two seemingly different subjects/ entities.
Who is to say that someone who excel in art must be poor in math or science? Who is to say that someone who is bodily gifted (as in good in dance and sports) cannot also be intellectually gifted? And who is to say that these are antagonistic rather than synergistic?
Deeming time spent in one particular area as time taken away from another and as such is a waste of time is assuming that the different fields are inherently conflicting and/ or antagonistic rather than complementary and synergistic with one another.
I am inclined to think that it is the latter.
"Great scientific figures ordinarily have had extensive interests and certainly have not been narrow technologists. From Aristotle to Einstein, from Leonardo to Freud, the great discoverer has been versatile and many-sided, with humanistic, philosophical, social, and aesthetic interests." - Abraham Maslow
Instead of attributing their achievements to traits of a genius, we should instead recognise them as the result of love for exploration and learning, and having the freedom for experimentation and to fail.
Even Albert Einstein said it himself - he is no genius; he is just passionately curious.
Rather than emphasising on the academics and interests that would insure our future, it might be way better to enjoy the freedom for some self-exploration and experimentation, which would cultivate our natural curiosity and love for learning.