Re: "something that isn't backed by anything of value can have value?"
Crytocurrency can be legitimized. In fact, it could be the replacement for plastic and paper sooner or later. It is very likely a good solution in the long term.
Something that requires you to burn large amounts of good energy just to pop out an electronic token at the end can't possibly be a good solution in the long term. It sounds more like the beginning of the end to me.