I suspect that Bitcoin is no longer a medium of exchange in the normal sense of the term in that it is now rarely used to buy goods or services. I suspect that now it is mainly bought and sold as an "investment". It is true that many of the shares exchanged on the stock market are bought and sold in the same way but at least most of them have an underlying value in company assets. Perhaps mining shares in exploration companies would be the closest comparison and even then there is some expectation that the exploration will find something of value.
This incredible jump in values has as much sense as if suddenly a group of people decided to start trading in Greek goverment bonds and sent the nominal €100 value to €18,000 just on the basis that they are promoted as an investment to make money by trading them.