All of this would be valid if we were lacking the resources to support our current population, and if every person consumed an equal amount. Unfortunately, certain people (i.e. the mega-rich and more generally Americans) are consuming resources at an unfair and unsustainable rate. You’re suggesting that scarcity is the natural result of immigration and population. In a vacuum that’s reasonable, but in real life we have a small number of people sucking up exponentially more than the rest.