Bitcoin have to be worth something in the same sense that a leaf of toilet paper isn't actually free - just very cheap. We don't know what the long term fair price of a bitcoin is and it isn't at all obvious that we are in a bubble.

For all the naysayers and the evangelists, at this point it is clear that cryptocurrencies have staying power and the broader market (not going to pick out bitcoin specifically) seems likely outlive the US dollar. Decentralised protocols are more reliable than the US government.