Is Bitcoin a Ponzi scheme?

People often ask me (I am an economics professor) isn't bitcoin a Ponzi scheme? Is it not a bubble that will burst soon and everyone invested will lose their money? Here's my response.

All currencies in the world are Ponzi schemes. We pay 3 dollars to our grocery for a loaf of bread. The grocer thinks that the bread producer will accept 2 dollars in payment from the grocer. The bread producer accepts 2 dollars because it thinks that the farmer who sells his wheat will accept a dollar from him. Ad infinitum. However, what is the dollar instrinsically worth? Since the gold standard was abolished after the Great Depression, dollars are essentially a Ponzi scheme based on convincing everyone that dollar is worth it's weight in gold. When enough people realize the truth that dollars are a ponzi scheme, they will switch to another currency that others believe in. The only difference in this faith is that it is a belief in each other's beliefs all specified by an algorithm. Patriotism is similarly an imagined social order whose time has passed. Transcendental humanity will be hosted by a network and a shared belief in a pre-specified algorithm.

Just as religions and the constitution are an imagined order to place society in harmony, and marriage is imagined order for a couple, so to currencies are an imagined order. Bitcoin is another example of an imagined order that transcends the national boundaries and state governments and allows us to exchange goods and store value through a belief in the imaginary value. Following are my two-byte predictions for 2018. (1) A steep depreciation of dollar due to a recession that will be triggered by an increase in unemployment and US budget deficit. (2) A switch in faith to currencies produced by algorithms on global networks.