None of which have thrived - all crumbling, failed or dead within.
The US has lasted slave free for about 150 years; Great Britain a bit longer. There are slave societies in history that lasted a great deal longer.
Yes, and for all measures of success, both are right at the top, when it comes to ranking high on those parameters. Do you honestly believe that a slave-free US is going to die out faster than a slavery-based US (one that was particularly so, in more religious times)?
There are slave societies in history that lasted a great deal longer.
Merely existing in geographical niches and isolated havens, slowly decaying into obsolescence, is no sign of success. Sustenance of success is key. To that end, all slavery-based states have failed.