I think I am joining this "thread" a little late but never mind.
I don't collect fountain pens- over the years, I simply have acquired a large amount of them (currently 22 Pelikans, 7 Viscontis, 8 Deltas, 6 Auroras, 3 Sailors, 2 Platinums and 10 Watermans, and there are others in other boxes...) They were each bought for love of their design and writing properties. And as for inks, I have probably got enough to last me for the rest of my life- and here I do confess to hoarding limited editions that disappear so maddeningly after a short while on the market- so I (currently) have 7 bottles of Edelstein Amethyst, 4 Amber, 10 Smoky Quartz and all but 2 of the entire Iroshizuku range, with many spares of my favourite colours (the 2 missing I simply didn't like), as well as over 20 Herbins, a dozen Sailor inks, Kobe inks and Akkernanns. So, on any view, I am truly hooked to FPs and the whole business of writing with them.
Why? Well, I agree with Graham Greene “My two fingers on a typewriter have never connected with my brain. My hand on a pen does. A fountain pen, of course. Ball-pens are only good for filling out forms on a plane.”
Collecting is the wrong word.
What we do when buying pens, is to bring into our lives things of beauty which enhance our existence. Pleasure is one of the purposes of living, and objects which improve our lives and our increase our happiness are things which we should not feel bad about acquiring- providing we can afford them and that obtaining them does not deprive our loved ones.
And every day, I chose some pens to take to work or for general writing (I do a lot of writing for my work and for my own pleasure) and every day my daily experience of life is enhanced by the pens I have with me. That sensation makes the money and effort that have gone into acquiring my collection entirely worthwhile!
So I will definitely go on buying new FPs and acquire more interesting inks!