The one and only fundamental factor pertaining to cryptocurrency is the security of the network. The security is increased by difficulty of cryptography, and number of nodes that increase the length of the chain.
Not only is the difficulty increasing, but the number of nodes is also increasing. The reason the price is moving up at an exponential rate is because as more people learn about cryptocurrency and share it with friends, the word spreads faster and faster until there is a moment that is described in social dynamics as "Critical Mass" where enough people have heard about a movement, that the entire population will hear about the topic without having to go looking for it.
In this case, there are enough early adopters that the word is getting out, to where every person and their dog wants to join the network - increasing the length of the chain and contributing to the security of the network and value of the currency.