> Cryptocurrencies and blockchains still don't seem to solve a real problem.

Have you ever wanted to send money to someone who wasn't in the same location as you? Alternatively, have you ever wanted to send a large amount of money without dealing with a large volume of cash, gold, or some other physical store of value (making the down payment on a house or car for instance)? Blockchains make it possible for you to do that electronically, and without the enormous and centralized infrastructure of banks, vaults, guards, armored cars, etc.