I think I would consider a player a pro only if he has sponsors.
If a player can play a year without winning any tournaments, and not even make profit, but still be able to play in tournaments and use your weekdays to practise because of sponsors then you've got a real pro.
But how many players live like that, if any?
And, as "Spiderwebman" (don't remember his az-name) once wrote in another thread: How many pros actually try to get sponsors outside the poolworld? If I were good enough to compete on a higher level I would definitely spend a lot of hours, and even money, to make a nice brochure and website, with my stats, bio, shortterm and longterm goals etc, and visit every single company in town.
I would send emails and call the newspapers about every tournament I was going to enter + send them results and perhaps a picture directly after the tournament would finish.
If the pros were working like this, I bet there would be more of both press-interest and sponsors. Unfortunately most of the pros feel that other people should do that job for them... Pity...
EDIT: Companies that sponsor for example a soccerteam gets something in reward. Not only their logo on the venue, but also tickets ++. If I were good enough to be a pro, I would tell the companies that sponsored me that I would do a random draw of every sponsor and the winner would get 2 tickets to the World Championship or US Open or whatsoever, to come and cheer for me in person. Then I would use some of the sponsormoney to cover the trip and hotel for them. I would also make a deal with the local poolhall that every company that I could get into the poolhall would get their tabletime for free for one night if I gave them a poolexhibition and made a tournament for them. Then I could offer that to every company who sponsored me too, and the poolhall would get more customers and the company would suddenly get something in reward for helping me... Just my 2 cents...