When they win, their minds will directly thinking about winning more and that make them continue playing gambling. They can't determine when they should stop gambling because the temptation to win become big. A real gambler know when he must stop gambling no matter what result he get. He will not chase winning if he think he doesn't have much chance and prefer to leave casino. That often happen to greedy gamblers and expect to win more because they don't see if gambling can make them lose all of their money