Correct me if I'm wrong, but I think it's also worth pointing out that from the point of view of judges, people losing money on ETH are really losing abstract Internet points. Even if it all happened in the same jurisdiction, would a judge be willing to consider that a theft has happened?
I don't think that's the material issue, but it is definitely possible that a judge would consider the matter too abstract to make a ruling over. But as a plaintiff or a defendant in such a case I really would not want to base my case on that.
Considering that the US government has decreed that Bitcoin is an asset and capital gains taxes are due when they are sold/spent, I'm inclined to answer yes.
