Will it bring you joy? I know that sounds pat, but it really does sit at the centre of a lot of this stuff. If a collection feels like a burden, it’s time to offload it (assuming financial considerations aren’t forcing your hand anyway, of course).
Everyone has their own triggers for things they love, and also relevant items they love the idea of owning. I recently bought all the Dark Horse Usagi HCs. They cost a fucking fortune. I now have various duplicates to offload AND the entire SC set. But this is one of my favourite comic series ever, and I felt like I had to have it. Fortunately, right now, I could also afford it. Also, I can sell these books for at least what I paid for them.
So I’m not all GO AND SPEND ALL THE MONEY, but if something is going to make you happy AND you can readily afford it, that seems like it could be a good option. If it’s also an investment, that helps too. (HC comics seem pretty good for that. Lots of Image stuff, e.g, goes OOS and so people selling those make a tidy sum if they no longer want a book. Hence me thinking “fuck it” and going full HC these days. Much sturdier; nicer to read; hold their value rather than losing it in a bloody instant.)