A small amount of alcohol has been said to be healthy. Your body needs some fat, gambling is stupid but it merely makes you lose money, tobacco is a seperate argument along with crack and all that.
Big Macs fit in the same boat. They have broken up marriages as well. The same can be said of sporting events and twinkees.
The bottom line is that your questions aren't really that illuminating (no offense) as American's tend not to ban things just because the aren't "useful". In fact, we tend to take pleasure in "useless" pursuits - collecting baseball cards, tinkering with cars, etc.