You are perfectly correct each person (or each state) following its self interest leads in this case logically to a slow motion disaster

Ethics, especially a la Kant, can help to address this shortcoming.

"Act only according to that maxim whereby you can, at the same time, will that it should become a universal law"

I like eating meal every day, but I cannot wish that this become the universal diet (especially of those 1b Indians). Therefore my ethical compass tell me to alter my food habits