That’s not necessarily true. The biggest resource constraint on the earth we can’t live without is food and we are extremely inefficient at producing it. Right now it takes large fields of biological crops, but the future might solve that problem.
That's a good point. The more I think about it the more what I said was a way of rationalizing not agreeing with the parent comment. Even if there were no ressource constrains it still doesn't feel selfish to me not to have children.