I don't know, betting on sports results should be pretty easy to game. The odds given are just designed to hedge the bookie's bets, not on the actually best guess on who is going to win. People are stupid, so will bet wrong in general; So you only need to figure out when the odds given do not match the real life odds to such a degree that you have a monetary advantage. You won't win every time, like the bookies do, but you should be able to easy get a positive expected value.
The problem with poker is that unless you are coning noobs, you are playing people at the same level as you. While if you get involved in huge population wide gambling, you only need to outplay the lowest common denominator.