There a difference between saying digital currencies will take over vs bitcoin being the currency that takes over or others with similar flaw. As the first line

There a difference between saying digital currencies will take over vs bitcoin being the currency that takes over or others with similar flaw. As the first line of OP's post points out he's not saying every single digital currency scheme will turn out to be ponzi schemes but I think he makes some very valid points about many of them. I don't think the early digital currencies we have are going to be the right ones to fulfill the type of future you are envisioning.