A bubble is when everyone is talking about cryptos, e.g. your taxi driver, the bellboy, etc. Outside of my close circle of tech colleagues zero people are talking about Bitcoin.
That's not really true...a bubble refers to the artificial inflation of the price of something because of some unjustified belief that it is more valuable than it really is. TBH I'm not sure if BTC is in a bubble state right now, but the argument can be made that the recent jumps in price don't reflect the actual value of the currency, and are therefore bound to drop