You are correct about point 5 that the devil is in the implementation details. But in the end I think that's not a problem (and that my explanation was actually

You are correct about point 5 that the devil is in the implementation details. But in the end I think that's not a problem (and that my explanation was actually incorrect). If you look at what happened to Ethereum when something went wrong, the community just decides to rollback the mistake. So maybe it's not "math and algorithms" as I stated it, but more like trust in "the community". The community just uses math and algorithms, but is not afraid to rollback when an implementation mistake was made. You are also correct that cryptocurrencies are not usable for payments. But I would add a "yet" to that. That's why I added counterpoint 3, that an easy to use app needs to be made for the regular public. I don't see this as a major hurdle, because nowadays even grandparents and kids can use a computer to go on the internet.