It is very easy to end up in a situation with bottled fountain pen ink where you own enough ink to supply a school for a generation. I’m lucky enough to not be in that situation.
Here is the thing: you don’t need to buy every single cool ink that shows up in your radar at once.
Like most of you that have been reading this site for a while: I like systems. I think it is partly connected to my personality and partly connected to my job as a Web Developer. I’ve had a mental system for managing how much ink I own at any given moment.
A hard limit of 5 bottles
Only once of each colour, unless I’m about to run out of it.
Only buy ink that I think is something I could use as my “main” ink for longer periods.
Give it away or sell it, if it is something you don’t use.
There are some inks you use more than others, and the only way to learn it, is by trying different things out. And stop buying stuff you don’t enjoy. For example: I don’t like Lamy inks. I don’t like the colours, I don’t like how they behave, so I don’t buy them. I don’t even consider them.
It is fine to have a lot of different inks if that is your thing, but you should try to do something about it, if you feel bad about it.
This is the question I always ask myself before ordering a new bottle of ink: can I use this to write with at work and at home in my main pen, all day, every day, for a couple of months?