Are there disadvantages not related to our economic system? Because without those I don't even think it would be a competition.

Lower genetic diversity, less species resiliency, lower growth for humanity across the board due to less humans exploring various problem spaces.... there are a lot of downsides to declining populations, depending on the surrounding circumstances/causes, just as there are upsides.

I’m completely drawing a blank as to why people having fewer children would be a bad thing for anyone, aside from the Idiocracy scenario. I can think of all kinds of reasons why it would be a good or neutral thing, but I can’t think of any downsides.

When there's more retirees and elderly people than younger workers to support them, how do you think our economic systems are going to survive?

Automation continues to reduce the fraction of people that need to work.

Also, we won’t need nearly as much new construction, which frees up a ton of workers.

I don’t think an aging population is likely to lead to labor shortages any time soon, at least in the US.

No one is talking about a labor shortage! The problem is a consumer shortage. Automation only makes it worse.

Aging population with a shrinking population means less people to buy goods. Automation means less people employed. This is bad for growth. Economic expansion requires increases in production and consumption.

By keeping older adults working and stopping age discrimination.

The downsides should be addressed instead of kicked further down the road. Less people on the planet is better, regardless of the economic and social challenges it presents.

> Less people on the planet is better, regardless of the economic and social challenges it presents.

To quote the dude, "Yeah, well, that's just like your opinion, man."