It's not human nature, but bad political organisation. The "leading role of the party" puts a single monolithic party in charge of everything, and if somebody senior latches onto a silly idea, it's hard to get shot of it.
Monolithic parties are autocratic, and that doesn't work well - look at Donald Trump for a contemporary example.
America never stopped any European war. They did join the winning side as soon as that could be identified with some confidence.
But most organisations prefer rent-seeking to profitable innovation. Rent seeking is a more predictable path to success. Innovation pays off about 30% of the time.
But you don't like it when they win. America was big on non-tariff barriers to trade until Trump came along, and now he's thrown them in too.
Trump did pretty well in killing off Americans during the Covid-19 epidemic.
He also wants clever innovative weapons designers, but doesn't know how to appeal to them. Trump has much the same problem. When I was young lots of clever people wanted to emigrate to America. Now I'm older clever people think of short terms gigs in America, but don't want to settlle there.
In the US the high-income groups are just as rapacious - it's the only place where wealth is more heritable than height - but less obvious about it.
Not so that I've noticed.
The US market is worth exploiting. They will be less enthusiastic when they find out how hard it is to find a competent and properly educated work-force.
Anthropogenic global warming doesn't respect national borders. Not believing in it won't make it go away.
In the same sense that Trump has "common sense". They haven't got the wit to understand anything more complicated than a scam.
Not that your got any statistical evidence that might support this point of view,
The Chinese one-child policy turned out to be a mistake. Pretty much every advanced industrial country has a higher population than it can sustain, and negotiating the path down to a sustainable population won't be easy.
But less-than-smart people are good at persuading themselves that they are smarter than everybody else. The Aryan master race didn't do all that well in Germany after 1945, and ended up importing a lot of guest workers to get the country going again.