As a store of value, it has many desirable properties. There is a fixed supply, it can be used anywhere with internet access, it is secure, and it is very inexpensive to hold. Gold, for instance, has a large potential supply, is very difficult to move and secure (e.g. vaults, armed guards), and typically requires you to trust a 3rd party (most hold gold IOUs, not the physical bars).
If you accept that there is a demand for such a store of value, then you must recognize the value of cryptocurrencies. There is also a great deal of potential value as technological solutions to the scaling problem are found, as well as new uses for Nakamoto-style networks.
