College Football is the only one I can watch with pure glee without an angle involved, as it is mostly from being semi burnt out, as even though under 40, I have been exposed to the lifestyle since childhood, and active since early teens.
It took until about age 20, for my father to finally convince me that I was always pulling for the "green team", no matter which school or team I was a fan of.
But pro ball on all levels, has had a huge interest drop in the last decade, as even my non-gambling friends rarely watch any pro ball except NFL now.
The NBA died when Jordan, Magic, Bird,etc..retired to most folks I know, as today's product is pure garbage to all that witnessed it's glory era.
With MLB's band boxes, juiced balls, and roidsters, killing the game to most of my non-avid baseball friends that watch just the playoffs now.
Modern amenities now available to those that grew up in past eras, plus their X-Generation kids of the PS2/X-Games age, make for extremely tough sells for pro leagues with many guaranteed contract thugs and their $100-plus tickets.