Actually there is an argument agains that value being very high, which we could call the Envy Factor: if a bitcoin were to be worth 1 million dollars, then the early adopters and hodlers would be trillionaries.  That means they would own a sizable slice of the world's wealth, which means other people's slices would be thinner.  

Indeed, that is what a government does when it creates a new currency or prints more of an old one.  But at least the government is supposed to return that slice of wealth to the people through the services it provides.  With cryptocoins, the creators and early adopters take that slice for themselves.

So, if the price of a cryptocoin got near that range, people may realize that a bunch of people is becoming absurdly rich at their expenses without having done any useful contribution to society.  They then may switch to a