I strongly believe bitcoin is not a bubble and i can't see it going down.. if they are a bubble how would they go down? i can't really see that scenario.. but many expert do believe so.. but i can't really see crypto going down. I even believe there will be integration with the current financial fiats.
Some of the people believes that it is a bubble, but who cares? As long as you don't let your self into that you'll be alright. You just have to take the risk as an investor.