I agree that the answer to humanity's most pressing issues is lowering our population, but don't think it's a non-issue.

The old keep aging out of the workforce, there's not enough young to keep a viable tax base, utter collapse. Here's where someone says tax the snot out of the rich. I'm down with that! But in a shrinking population, they won't be rich long. Directly or indirectly, all of their money comes from us.