I think they're actually illegal in the US. There was someone who posted a link to a bank who tried that and got shut down by regulators. The reason is because

I think they're actually illegal in the US. There was someone who posted a link to a bank who tried that and got shut down by regulators. The reason is because the government believes money should be put to work - otherwise, it's a negative asset because you need to hire physical security, cyber security, engineers, support people, etc. to service the money that is doing nothing. By the way, the negative asset logic is one reason is why Warren Buffet hates Bitcoin.