I think it's moreso that there's a pie... and billionaires/millionaires/VC/PE want people to worry about too many people instead of a very greedy, wasteful few.

Now, you can have too few youngsters in the workforce, as a few countries are about to find out.

Could keep the current population AND have a high standard of living WITHOUT it being wasteful: and GOOD NEWS EVERYONE, it's a fun engineering problem! (but it's also a policy problem and requires intentional change) - e.g., reshaping manufacturing away from landfills, agriculture away from crops humans don't end up eating, companies away from stock markets and toward worker control, governments away from lobbyists and towards citizen control....