Also recall the nature of the food chain. Growing animal flesh requires 10x the plant inputs compared to consuming plants directly.
What an improvement!
It must be the vegan's fault.
First of all, again, the vast majority of that slash and burn agriculture is used to feed animal livestock.
Second, even if that agriculture was used for human consumption instead of animal livestock, it would again require 10 times less land to feed humans than it does to feed animals that are fed to humans.