This would be tough in practice. First you'd have to make sure any player or manager who places a bet only uses a platform that is transparent. Right now that doesn't exist. Second, they would literally have to bet on their team to win every single game they play in. If they only bet some of the time, it is going to create some huge conflicts where they might not try as hard or make different decisions based on whether or not they bet. Now if you really want to extend this out, I do wonder if a smaller league would allow teams to make money based on their wins and losses. Although not technically gambling, it would kind of like they are betting on themselves to win. Win more games = make more money.