Yes, Bitcoin is a bubble in terms of financial relations, because it is not based on financial relations,
but on a new technology. For the means of payment this is not enough. However, no one knows what will happen to Bitcoin. He may die in a few days, or he may exist for centuries. Time will tell.
If bitcoin lasts that long then it was not a bubble, one thing that some people may miss is that when a new technology is created the volatility and the price movements are very similar to what you see in a bubble created by speculators, so I really believe that what we are seeing is something similar to that and many people which said that bitcoin is a bubble will have to recognize their mistake.