A merchant once appeared in a village in Africa and announced to the locals that he was buying monkeys at $100 apiece.
The people decided this was a very good offer and started catching monkeys and selling them to the merchant for $100 each.
The next week he announced he was now buying monkeys at $200. The people rushed into the forest again, caught a great many monkeys and sold them to the merchant for $200 each.
The third week the merchant announced he was now buying monkeys at $500. Even the laziest got up and started catching monkeys, until they had caught them all and the man bought them at $500.
In the fourth week the man gathered everyone and announced he was leaving for a while, but when he returned he would buy monkeys at $1,000 apiece. All the monkeys collected so far he locked in a cage and posted a guard in front.
After he left, the people wondered where to get monkeys and wandered the jungle all day. At one point the cage guard told them he had started selling monkeys on the sly at $700. The rich bought as many as they could; the poor took loans from the rich and bought monkeys too.
Then came the moment when the merchant was supposed to arrive and buy monkeys at $1,000. But he never came… and the cage guard had vanished! And that is how the tale of bitcoins and cryptocurrencies ended…