Bitcoins should be regarded as assets, or really equities, not as currencies. They are each little business plans — each perceived to create future value. They are not stores-of-value, but rather volatile expectations on the future success of these business plans. But most ICOs probably don’t have viable business plans; they are truly castles in the sky, relying only on momentum effects among the growing herd of crypto-investors. (The Securities and Exchange Commission is correct in looking at them as equities.) Thus, we should expect their current value to be derived by the same razor-thin equity risk premiums and bubbly growth expectations that we see throughout markets today. And we should expect that value to suffer the same fate as occurs at the end of every speculative bubble. 

If you wanted to create your own private country with your own currency, no matter how safe you were from outside invaders, you’d be wise to start with some pre-existing store-of-value, such as a foreign currency, gold, or land. Otherwise, why would anyone trade for your new currency? Arbitrarily assigning a store-of-value component to a cryptocurrency, no matter how secure it, is trying to do the same thing (except much easier than starting a new country). And somehow it’s been working.

Moreover, as competing cryptocurrencies are created, whether for specific applications (such as automating contracts, for instance), these ICOs seem to have the effect of driving up all cryptocurrencies. Clearly, there is the potential for additional cryptocurrencies to bolster the transactional value of each other—perhaps even adding to the fungibility of all cryptocurrencies. But as various cryptocurrencies start competing with each other, they will not be additive in value. The technology, like new innovations, can, in fact, create some value from thin air. But not so any underlying store-of-value component in the cryptocurrencies. As a new cryptocurrency is assigned units of a store-of-value, those units must, by necessity, leave other stores-of-value, whether gold or another cryptocurrency. New depositories of value must siphon off the existing depositories of value. On a global scale, it is very much a zero sum game.

Eoin Treacy's view

I agree it is more appropriate to think of bitcoin and the other cryptocurrencies as assets rather than currencies which they are not. They are at best a reflection of the economic value of the network they represent. 

The mass proliferation of cryptocurrencies has occurred because the barrier to entry is getting progressively lower. While bitcoin is still by far the best capitalised of the cryptocurrencies the massive number of initial coin offerings means overall supply is increasing. More than any other factor that will contribute to an eventual winnowing of the number of cryptocurrencies as the business case for each is weighed by the market.