Bitcoin holds value because of the people who uses it. This crypto currency has a unique decentralized feature thats why it attracts investors or even ordinary people to use it.
Yes it has no proper price because the market dictates in other words those people who uses it dictates what would be it's price value.
Bitcoin is one of good example of a volatile currency because no individual has the power to control it but the majority itself decides if this digital curency is over or will continue to pump.
Throughout the years bitcoin has survived countless bubble but look at bitcoin now.