I use fountain pens almost exclusively at work and at home.
I enjoy using a finely made writing instrument. It makes me feel better about myself and improves my handwriting as I think about how the ink flows on the paper.
I do not see the competitive side of this as important to me, since I will not likely be collecting pens which are so rare others will not have one like what I have bought.
I also like preserving a part of history, even if others only rarely look at or have an interest in my collection. I have framed a few magazine ads which match particular pens I have, which is part of what decorates the walls in my private office.
And it is cheaper than vintage automobiles.