There is in fact fundamental value in bitcoin. It costs an increasing amount of electricity to "mine" the marginal coin. That cost is reflected back to older coins as the new marginal cost. No one will mine unless market exceeds cost. Some people set up their operations in hydro rich countries to arbitrage electricity cost. Now, you may think bitcoin is a silly idea as a currency, and I do, but the thing has an embedded value as a pure collectible. Why anyone would want to collect them is beyond me, but this is what it is.