There's nothing wrong with a healthy profit margin, per se. The potential problem here is that we have a de facto monopoly in many regions which controls access to FOOD.
I don't think we've seen that scope here in the US... Yet. But given the number of guns, "it's a when, not an if" if the politicians allow extreme food scarcity to happen in a wide area.
panem et circusensus (bread and circuses)
The way I see it is that any food desert either exists because it is not profitable or because nobody has taken the initiative to offer a profitable service. Obviously I could be wrong, but I have a hard time seeing how a megacorp is denying access to food.