The random rolls on loot is what prompts it. I have no use for this armor piece right now; should I throw it out? Well, if it’s got 60+ stats, then no, because it might be useful to a future build. Double that incentive if the armor was available for a limited time. You don’t wanna know how many Solstice pieces I have right now. Triple that incentive if it’s an exotic armor piece with a good roll. Doesn’t matter if I’m probably never gonna use it; I MIGHT, and that’s what matters. Plus, what if a future patch—or future bug—makes it OP? What about these duplicate weapons? Surely some of them can go, right? Well, not really. They all have different perks, and they’re useful for different things. Some of them are the copies I save for my alt characters, but they’re in the vault because I’m not using them right now in my loadouts. Some of them are cool-but-useless or niche guns I bring out every so often, mess around with for a bit, then stash again. A couple are sunset weapons I keep for sentimental value, or on the off-chance they’ll be refreshed in a future season (‘cause I have decent rolls I don’t want to lose). Some are exotic weapons which I’ve already infused up to a useful power level, so I don’t want to have to retrieve them from collections again. And finally, some are useless garbage rolls which just happen to be Pinnacle drops, so I stored them in my vault for my alts to later retrieve (thus raising their maximum average Power levels, speeding up their grind to 1260). And probably forgot about them, subsequently. The point is there’s a lot of different reasons to keep a lot of different items in your vault, and they usually all lead back to the Big reason: because it’s harder to find again than it is to just keep around. In fact, in all too many cases, it’s impossible to find it again. It’s a frustrating reward system that makes me feel like garbage, but it’s addicting and it keeps me playing.