Here's an imponderable I am pondering sometimes:
What makes for a well-rounded individual?
Do you need to know your classics? Classic books, plays, films?
Do you need to know your contemporary culture?
Do you need to know what is going on in the world?
Do you need to be well-versed in a specialty field?
Do you need to know your basic science, physics, astronomy... ?
Do you need to know something about art in general?
The tempting thing is to answer "yes" to all of them, but the issue quickly presents itself that each of those, well done, is easily a full time study, leaving no time for all the others.
... Which of course gives us the conundrum, is it best to compromise and know a little in all of them, or to specialize?
How about the scientist who is a world leader in his field, but who has no idea who Tom Cruise or David Bowie are? Is he to be pitied compared to the person who can talk to anybody about any culture, but who will leave little mark on the world in his lifetime?
UPDATE:
I agree with commentators that interest must be the drive.
But this is for individuals. We also judge each other, and make demands. This is perhaps most clearly felt in the school system. Students are required to learn many things that only a tiny minority of them will ever use in practice. The reason for this can only be society's (that's all of us) desire to raise well-rounded individuals.
... Which is... good? I guess? Or would we all ultimately be better off if all of us only had to study what we are really interested in?