I wish this "chess makes you crazy" line would just die. If anything, chess kept Fischer sane. Chess gave Fischer focus and forced him to interact with people. He only truly went off the deep end after he stopped playing.
I'm sure that if Congress really wanted to directly regulate the sell of automobiles, they can find a way to appeal to the constitution's commerce clause. I know the courts have tended leaned more towards the 10th amendment in recent decades, but they still tend to give the commerce clause a very broad interpretation.