Isn't that basically what bitcoin is?
He can hardly buy anything with it. We just give it value for the sake of giving it value.
Matter of fact, let's do just that for the heck of it, see how far we can go with it. I'll pick up a rock and call it Akorn and put it up for $10. I'll buy it back for $10 and let's see how much it'd be worth by the end of the year.
You are saying rocks have no value? Lol. Of course they have a value. Even a common rock has a value, but less than a cent because it can be found anywhere. So no. No one is going to buy your "Akorn" for $10. Why would they? They could literally pick a rock for almost free of cost (minus a little labor lol). But lets say, you found a piece of meteorite (meteorites are rock too

) and you want to sell it for $10. Someone is going to buy it and then sell it for $100. Meteorites are hard to find, hence expensive.
So if bitcoin was like picking up a rock, it would be dirt cheap. But guess what, they aren't dirt cheap. Now, why is that? You will know if you try to learn about bitcoin and how the system works.