Bitcoin - the money of the future, investment or fad?

As many of you are no doubt aware, the price of Bitcoin has shown a lot of volatility over the last year.

Please share your thoughts on the following question, or any related topic:

Do you think cryptocurrencies such as Bitcoin serve any legitimate purpose? Are they just a passing fad, or should they be viewed as opportunities that may revolutionize the world of finance and beyond? Do they pose any threats to the global economy?