"it is often cheaper to buy the equivalent of a hamburger, fries, and coke at McDonalds, Burger King, or other similar stores, for less than you can buy the ingredients at the supermarket. This is actually a "known thing" which has been factually verified."

I've worked fast food and grocery stores - the only time a grocery store is more expensive is when you go 100% brand name goods, and even then the price difference in total is a couple bucks.