I’ll give you similarities of the Bitcoin with a Ponzi scheme:

From wikipedia: "A Ponzi scheme (/ˈpɒn.zi/; also a Ponzi game)[1] is a fraudulent investment operation where the operator generates returns for older investors through revenue paid by new investors, rather than from legitimate business activities or profit of financial trading."

Bitcoin's only real value is that of the chance of being adopted as currency. For it to become a currency people have to start buying bitcoins, as it is the only realistic way to get hold of them. So the only way to make value for the current holders(older invenstors) is more people buying into it(revenue paid by new investors).