Slavery and capitalism
Don Boudreaux misses the point. He's trying to refute the idea that modern-day capitalist wealth is the product of pre-abolition slave labor. He responds to a questioner at one of his lectures:
She anticipated my response. "Not directly. But the capital that made these innovations possible was extracted from slave labor. The wealth accumulated by slaveholders is what financed the industrialization that makes today's wealth possible." ...Astonishingly, he misses the point completely. No one says that slavery was sufficient to spark the industrial revolution. The argument is that slavery was necessary. That is, modern prosperity is the product of slavery insofar as the economic products of slave labor were necessary to bring it about. This is an empirical question that historians debate (for example, did the explosive takeoff of textile production in Britain depend on a steady flow of cotton from the US slave states?), yet Boudreaux never addresses it at all.
Collecting my thoughts, I pointed out that slavery had been an ever-present institution throughout human history until just about 200 years ago. Why didn't slaveholders of 2,000 years ago in Europe or 500 years ago in Asia accumulate wealth that triggered economic growth comparable to ours? ...
And why, having abolished slavery decades before their Southern neighbors, were Northern U.S. states wealthier than Southern states before the Civil War?
The fact is that slavery disappeared only as industrial capitalism emerged. And it disappeared first where industrial capitalism appeared first: Great Britain. This was no coincidence. Slavery was destroyed by capitalism.
So yes, duh, capitalism and chattel slavery are antithetical. But you don't have to be a card-carrying Marxist to appreciate the idea that sometimes one system of social relations will contain the seeds that give birth to an entirely contradictory system of social relations. Just because capitalism abolished slavery doesn't mean that capitalism didn't depend on slavery to get started.
As for why other slave societies didn't get wealthy - well, that's because they didn't have the many other factors that were necessary to kick-start the industrial revolution. That doesn't mean that slavery wasn't also one of those factors.