Bitcoin gain value because people believe it's worth something, meant to be a currency but lately bitcoin has lost its utility appeal and most people just treat it as an investment object to generate profits. It has been proven as the price swings significantly within minutes, even rise and fall as much $1000 is a common thing these days.
Bitcoin isn't a bubble, but if this condition continues, bitcoin may not be used as means of payment due to scale problems still unresolved.
It is going to be difficult for btc if the transaction does not improve and the fees are going high like always . Thus no many people have switched to Ether or other altcoins where the transaction is almost instant and negligible fees. BTC as right said would be used mostly for the cold storage or only for investment purpose only.