Read Professor I. Nelson Rose‘s answer here. A glimpse: “I am often asked whether Internet poker is legal. The answer is probably not, but the chances of actually getting into trouble are very slim. How slim? You have a better chance of winning the final no-limit Texas Hold ‘Em tournament at the World Series of Poker. After all, someone wins the WSOP each year. No one has ever been arrested, let alone convicted, for merely playing poker on the Internet.”
It’s also permissible to day trade — sometimes.