Compulsion is the line. Compulsion and destruction. If you ignore your responsibilities to play chess, and you spend all your money on chess sets and tournaments, that's an addiction. If you love chess and play at every opportunity, but don't let it get in the way of your responsibilities, and don't spend your gas money on chess, then that's a hobby. A lot of Candy Crush and other P2W mobile game players spend more money than they can afford, and they play compulsively, because the game is literally designed to be addictive. There's a lot of addiction psychology that went into the design of these games, using the same principles that casinos use for slot machines.