What ought to be is what benefits the tribe. More people benefit the tribe, because you then have expendable males that can be used to pillage the neighboring tribes. Unless you have depleted the environment (e.g., overhunting), there is no incentive to abstain from breeding as much as possible.
"We also spent millennia believing the earth is flat"
How does that even translate into more or less births?
Yet, avoiding putting women in risky jobs (e.g., hunting) does translate into lower mortality rates for fertile women and, thus, allows more babies to be born.
Men cannot give birth, so they are more expendable and are given risky tasks, like hunting and protecting the tribe from other tribes. The average 20 year old woman is much more valuable than the average 20 year old man.
Perhaps a few decades from now, saner people will arrive at the realization that a woman's first career should be motherhood. A woman's best years should be for her children, not her employer.
"... or the wife works while the man take care of kids"
Then wifey starts seeing hubby as a sexless entity --- sort of like the son she never gave birth to --- and loses attraction for him.
"... it isn't a gender thing. It is a money thing"
Humans spent millennia as hunter-gatherers. Men hunted, women gathered. Men protected and provided, women nurtured the children. If women provide and protection is provided by the state, then men are useless. Birth rates fall. Religious people who live according to traditional gender roles then outbreed the atheists.
Antibiotics are some 90 years old. Before then, STDs were a death sentence.
K-selection is civilization. r-selection is feralization. One of the goals of religion was to tame r-selected behaviors and to encourage K-selected behaviors.
> the message that some politicians have been using ("trade agreements are evil!" "immigration is bad!" "the EU is making us abuse you!") has taken hold
Or, perhaps, the dissatisfaction was there all along, and the politicians are merely exploiting the pain of a faction of the electorate. Humans are tribal. They don't become tribal overnight because a politician told them to do so.
It is safe to assume that people with non-trivial power are very seldom sincere when making public statements.
If Dubai's elite's descendants will be riding camels some decades from now, then why does Dubai have a national wealth fund?
The truth is that Dubai's wealth fund may invest in YC or in VC funds, and some of those mocking Dubai's future will be working indirectly for the elites that run Dubai. To distract people from such master-slave reality, a bit of self-deprecation can be charming.
Quoting Samuelson, if a man marries his maid, the GDP goes down. That is how smart GDP-based arguments are. Wait until the population gets close to the carrying capacity again, and let's see how your GDP argument holds.
Perhaps you only know tech oligarchs. But if you look at the list of billionaires, you find also mining oligarchs and fossil fuel oligarchs. So much for the argument that raw materials do not matter...
Physicists invented nuclear racketeering, which made them celebrities in the 1940s and 1950s. We live in the age of the MBA, not in the age of the scientist. That golden age is gone, unfortunately.
Or, alternatively, reproduce abundantly and use your children to make alliances with families that actually do matter.
You're advocating having few children in a thread related to Saudi Arabia, a kingdom whose founder had 20+ wives and some 100 children. That is how all the warring clans in the Arabian Peninsula were united and pacified: by marriage.