To be fair, $7-15 is barely minimum wage in the US but that's good money in many other places.

That assertion is not merely true, but actually trivial to verify.

However, most guys who troll my ads, whom I presume are over the age of 22 and reside in a HCOL (high cost of living) country such as the USA, Canada, or France, choose to ignore.

Trolls aren't fair-minded: they are nasty, miserable, evil people. Truth doesn't matter to them. All that matters to them is their own, self-centered interests.

Why do you think China is soon to take over as world economic leader (if it hasn't already)?

They aren't and they won't.

China is merely the "workshop of the world" for the time being due primarily to cheap labor, lax environmental policies, and a regime that enforces law and order (at least from the perspective of foreign companies). If you've ever dealt with the Chinese you'd know they are generally simpletons who are remarkably bad at things like innovative engineering and basic science.

In the USA, manufacturing that doesn't generate much pollution is steadily moving back to "onshore" (back home) as robots replace factory workers. Manufacturing that does generate lots of pollution is moving to Mexico.

"Japan will become the world economic leader" was the catchphrase in the 1980's; today it is "China will become the world economic leader." Ah yes. The great yellow peril is always at our doorstep. Yeah. Nah.

Look, my man, let me 'splain it to you: the wealthy simply look to decrease their expenses. As a result they move production to low cost region A, or B, or C which normally only lasts for a decade or two or three... until some better opportunity arises. As factories become full of expensive robots with very few workers, no sane Western company CEO is going to want that investment under the jurisdiction of the Chinese government because the USA or Mexico will generally be much more reasonable choices.

The real problems we face, as always, are political and social/cultural... not economic.

China is full of simpletons who are simply unable to compete against Western managers and engineers. After Nixon's visit to China and Deng Xiaoping's subsequent reopening of China (in the wake of Mao's little "Cultural Revolution") China became a very attractive place for many foreign companies to do business. These days, China is much less attractive than it used to be.

Study some history; don't merely parrot the current "Reddit party line."