Early on, God commanded us to be fruitful and multiply.
He told us to subdue the earth.
At their core, population control advocates simply don’t trust God to put His blessing on the fruit of what He has commanded.
Without faith it is impossible to please Him. And without faith it is impossible to enjoy God’s richest blessings, in the here and now, and unto eternity.
We distrust and disobey God at our own peril, and to our own great disadvantage.