Here are only some of the reasons why cryptocurrencies are not going away any time soon:
Regulation is not the enemy. A lot of people are afraid of regulation, but regulating cryptocurrencies will bring many benefits. Over the long term, regulation will make cryptocurrencies safer and will prevent scams. In addition to this, it could help to establish safe websites where everyone could engage in trade.
Scarcity. There is a limited amount of bitcoins that will ever exist. Which means that their price will probably rise in the long term.
Decentralisation. No particular bank or government is in the control of them. This essentially means more freedom for end-users.
They cut out the middle man. With cryptocurrencies, there may no longer be a need for banks. This means less transaction fees and more time saved.
Security. It is almost impossible to mess with the blockchain data, because of the public key available on all nodes. You would have to change data on every single node in a network, if you wished to permanently distort the data. Unlike banks, cryptocurrencies dont keep all of their data centralised. This means that they will eventually be much more secure than banks.
Blockchain technology. We are seeing more and more fields adopting this technology because of its qualities. I will not go into details why this technology is so good, but it is clear to everyone that this technology is the future. It will lower transaction costs and make every party involved better off.