You still haven't provided evidence of "legitimate economies transacting in Bitcoin". El Salvador accepting Bitcoin as legal tender in the future is not evidence that a legitimate economy has been transacting in Bitcoin in the past. One of the criticisms of Bitcoin is that skepticism is always answered with hype and promises, and you're kind of doing the same thing here... Where's the data backing up the success story?
As I understand it, people in the developing world with high inflation are putting their money into crypto. Also, people with money to invest put it in crypto (both the "very rich", but also regular slightly more technical or otherwise inclined folk). Both of these aren't day to day transactions though.
To escape inflation you buy dollars or even gold ingots, as always.
Crypto is just a risky investment for that people, not savings.
If the environment is unstable in some developing country, dollars and gold are inconvenient to hold, while crypto is both easy to own, easy to /really/ own and also fast to transfer.
Risky, well I guess - especially in the short term. But long term it appears to have done very well.
and many other examples. Stephen is just wrong here, like, 6+ years out of date wrong. His arguments hold no water today.