I think part of that is the time involved. Watching Bolt takes 10 seconds -- the entire event can be shown on the evening news. Not as many people sit and watch

I think part of that is the time involved. Watching Bolt takes 10 seconds -- the entire event can be shown on the evening news. Not as many people sit and watch the 10,000 meters and even less an entire marathon. The more time involved, the more likely it that you are a fan of the sport/activity.