In the example in the movie is that, just as they head the procession, luxury foods and can use resources is extravagant, but at the end of the procession of people ate only protein bar made from insects can only curse.
In the example in the movie is that, just as the train was a luxury food. The lavish use of resources. The end of March, but people only eat protein bars made from cockroaches only.
The movie is that only the head the consumption of food. And can use the resources can be wasteful. But the people at the end of the eat only bars protein made from cockroach.