Are you buying things just to collect them? Or do you have a collection of stuff you bought when you were younger and are holding on to that for nostalgic reasons?

I don't really actively buy any retro stuff anymore unless I'm wanting to play some particular game or something. It's just too expensive.

But I would have a really really hard time selling things with sentimental value. Maybe that will change someday but for now it's too recent (20-30 years ago for me for most of it).

The other thing is, unless you really need the money (or space) now... Physical video game paraphernalia is not likely to go down in price over time. It necessarily becomes more scarce as time goes on. So that's something to consider even if you're just collecting to gain value.