The other thing is the formatting of a pool tournament. Football, Baseball, Basketball are all aired LIVE. With Football there are multiple games aired on any given Sunday on multiple different channels, then that is pretty much it until the next week (not counting the single games on Monday and Thursday.
A pool tournament can take 5+ days with 3-5 matches a day on the streaming table. Looking at an average of 1hour30mins per match and let's say commercials and everything else all fit into that 1hour 30min time frame, you are looking at 6 hours of TV time a needed to broadcast 1 days worth of a pool tournament... that over there course of 5 days... if you want to broadcast a pool tournament live, you are looking at roughly 30 hours of pool spread over the course of 5 days.
I doubt 30 hours of pool total has been broadcast on TV in the last 7 years...