Gambling is different than becoming a professional pool player. A professional pool player can hustle and make more money doing other things related to pool, lessons, paid appearances, merchandising, sponsorships, etc... Of course, all of these things require you to have personality and looks that will sell.
As far as gambling, most people aren't going to buy anything from drug addled cigarette smoking tatted up hustlers living out of a car who will rip off anyone any chance they get so they can survive. You'd have a better chance starting a rock band and making it big.
The reality is, at least in the US, that neither a gambling or professional pool career is going to take care of you when you or your loved ones get sick or are beyond your prime and forced to retire. Maybe 10 out of a million can pull that off somehow. Otherwise, you are going to be living off of someone else's graces when you can no longer perform at the highest level, probably at about 40 or 45 years old. Two good examples of players who have realized this are Alex Pagulayan and Fedor Gorst, both are investing as much time and effort into branding and merchandising as they are their pool game. Of course, both of these guys have access to healthcare that the US players don't, so they don't have to worry about that as much.