"It is not a bubble" is what we hear every time from people invested in an asset hoping it will make them rich.
Before the dotcom bubble burst, dotcom shares were not a bubble said the people investing in shares. It can only go up they said. NASDAQ is going to the moon and will reach 100.000. They said. And then they lost.
Before the housing price bubble burst, house prices were not a bubble said people who were borrowing more and more money. It can only go up they said, because there will never be more land. They said. And then they lost.
It is so predictable that it is sad.
Bitcoin is currently as big as the ruble. Think about how big Russia is, withs its 140 millions inhabitants sand the second or third oil reserves in the world ( among many other things ). Bitcoin is as big as that, with no economy to back it up.
If Bitcoin grow by 20x, it will be in the same league as the USD. Think about it: a currency that currently supports up to 500k transaction a day ( which couldn't power a medium-sized city ) nearly as big as the USD.