...not a guaranteed value of the Bitcoin makes the price move is not fair.
Life is not fair. The fact that bitcoin is not guaranteed by state violence is the very reason it will succeed, the very thing that makes it unique from all violence-backed state promissory scrip.
No, bitcoin will not last forever. But it will almost certainly get us through the end of capitalism.
Most of us will can't predict the future of bitcoin. But if all people here in the world are using bitcoin, maybe the future of this will last until next generations. Because we all know bitcoin is most promising currency of all time.