Just as we ask what makes the phillipino's so dominant in pool you can have the same discussion of the brits and snooker.
Currently there are two non-Uk players, Marco Fu of Hong Kong (learned to play snooker in Canada) and Ding Junhui of China, in the top sixteen this season. This the largest amount of foreign players in the top sixteen since the 80's when 3 Canadians held high rankings (Bill Werbuniuk, Kirk Stevens and of course Cliff Thorburn).
It's also not that easy to get on the main tour. Not just anyone can turn up and play as there is a lengthy qualifying system in place. There are many players in the UK knocking in century breaks on a regular basis and I bet any of them would give the phillipino pool players a tough game on the snooker table.
Finally in regards to money, the prize funds are VERY top heavy. Here is the breakdown for the World Championships
Winner: ?250,000
Runner-up: ?125,000
Semi-finalists: ?52,000
Quarter-finalists: ?22,000
Last 16 (round 2): ?14,000
Last 32 (round 1): ?10,600
Everyone else coming through the qualifying rounds gets nothing. But on the otherhand if you are in the top sixteen, which automatically qualifies you for the last 32 in every ranking tournament, you can go through an entire season without winning a single frame and still come out quite well monitarily.