They definitely notice, why do you think they’re pushing the birth rate and great replacement theory BS so damn hard? They want everyone young, broke and uneducated so they can keep the grift going.
They would, then, but that is not now. Right now they are concerned with us not having enough children, because capitalism requires population growth, and, as places become richer, they have fewer children. The most industrialized places are in decline, outside of immigration. So this is where you see the consternation of the rich and powerful.
Doesn't work, places have tried that. The collection of conditions are not conducive to it, for most people. That's why it is getting very "handmaid's tale" in rhetoric from a lot of the rich and powerful.