The bitcoin's value lies in the network, this network enables value transfer across the globe. A bitcoin without network worth nothing, just like a telephone disconnected from the line

But with network, bitcoin can be used to store/transfer value, it is like some kind of value transfer container with limited supply but unlimited capacity. Each container's floor of value depends on how much value they store/transfer daily, divided by the number of containers available daily, so it is very volatile

However, to make this logistic system working, there is an operating cost (mining infrastructure), which decided the production cost of each container, means you normally can not get a coin at a lower price than the mining cost, that is the floor of bitcoin's value in reality

Currently people are trying to collect as many containers as possible, since they foresee that those containers will be used to store/transfer large amount of value in the future

By the way, there is no floor of value for dollar, only a consensus, since it cost nothing to make. Once this consensus break and people refuse to accept dollar as payment medium, they might be forced to accept dollar by man with guns