I think McDonald's is a lot more responsive than most people give them credit for. I mean, Super Size Me killed their super-size menu. Then they tried salads, but pointed out they couldn't sell them because, well, people don't want to eat salad. The whole breakfast-all-day thing is basically an easy, comforting way for them to differentiate and since their menu is so prefab and regimented it barely impacts their menu at all. People also forget that McDonald's holds $28B in real estate and has 15,000 tenants. Most of those sites are in extremely valuable areas and those tenants are stable. It further muddles the correlation between "big mac cost" and "big mac price" because they don't necessarily need to make money on, you know, food. McDonald's can subsidize the price of a Big Mac and still make money because they're selling them (in bulk) to their tenants.