Lot's of people. Just because you may not care about sports doesnt mean massive amounts of people around the world don't. Several countries will win their first gold this year. That's a national achievement. Several sports will be included for the first time this year. That is a whole set of people who get to see their favorite hobby included in the games. Many new world records will be set which is an example of technology, humans, and science all working together to achieve things thought impossible before.

Many people care about the Olympics for many reasons.

I for one enjoy watching it. A bunch of people I know like to watch it too (and they don't really "do" sports normally).

At least in the UK, it gets prime-time billing on one of the major BBC channels.

I'm not a sports person at all but every two years, my wife and I watch tons of Olympics. It's really weird for us since I probably watch 1 hour of sports per year but during the Olympics (Winter and Summer), we will sit down and watch 3 - 5 hours each day. Sports that we have no interest in outside of the Olympics.