Your implicit criticism of people who have only a few interests in life actually makes me wonder how then should one develop other interests?
Now, many might say that interests cannot be "developed" (they need to be in you already, even if latent). But I tend to disagree. But I don't know how to develop interests.
This question actually points to a much broader, relevant and therefore important question: how can I get rid of ignorance/darkness and laziness/inertia? Also, how can I help another person get out of it? Often it is the case that I would like to love topics like history or economics but I simply don't find them all interesting.
How can I develop curiosity and wake out of ignorance and inertia?