Essentially, the only thing that causes the price to go up is new people buying into the market. That's the only "value" here. This is why it's called The Greater Fool's theory, is you keep passing the bag over to the greater fool who will pay more for it than you.
For investments of which the only purpose is to make more money, right.
Of course it's not that black and white, since every investment technically has at least two utility purposes: 1) hedging 2) emotional utility (the false hope of getting rich).