Are fountain pens actually worth it?

If you write by hand at all, yes — for reasons that compound. Zero-pressure writing is easier on the hand over long sessions. Bottled ink costs pennies per fill. A good pen is a buy-once object: the popular starters survive decades, and gold-nib pens outlive their owners.

If you write three words a month on sticky notes, a $2 gel pen serves you better. The value case is proportional to how much you actually write.