Many people buy fountain pens as collector's items.  The history is fascinating, the range of different makes and models is huge, the challenge of tracking down a particular pen in a particular color, etc.  can be great fun and following the development of ink flow controls and filling systems can be very interesting.

At the same time, an increasing number of people are turning back to fountain pens for every day use.  In an age when most of our correspondence goes via the keyboard, it is a pleasant change to pick up a nice pen for the more special occasions.  In fact many people find writing with a fountain pen so satisfying that they use it for all their hand-written work - including the shopping list!

I also find that most fountain pen enthusiasts have more than one pen in regular use - maybe with different nib styles, different colors of ink or simply an every day pen to carry about and a special one which stays on the desk.