Because they host a demographic that is nearly triple our entire population. And thats in thrir country alone, not even accounting for the presence of Indian immigrants in other countries. Ours included, (assuming your American). This question reaks of American exceptionalism. Yes. I'm American. Yes. I love my country and most of our culture. These are just facts. Bollywood is huge, and the music and dancing are phenomenal. in my opinion.
What kind of Indians are you asking about? American Native Indians? Any Asian Indian? People that live in the Indian Ocean? Is there something cultural that I am missing? Why would Bollywood be important to anyone not profiting from it?
For the same reason americans think they are the only country in the world with "freedom" I guess.