Doughnuts and Economics

I had a craving for doughnuts today so my sister and I went down to the grocery store to get some because I've never seen a doughnut shop around here. My sister lives near a really ritzy mall that seems to have everything else. But to be honest, I only ever see doughnut shops in economically depressed or, in the very least, slightly sketchy areas. Why is that? And before you say that's because rich people won't eat fried dough, there are TWO pretzel stands in the mall.