Y'know, for an accessory with a 2% unbox rate, I've seen them drop pretty regularly... or rather, irregularly. I unboxed mine on my second Prize Box, and I've heard at least four other instances where it dropped on someone's first or second unbox.
For something that's almost as wonderfully rare as wings, the RNG is certainly rather generous, hmm?
To be fair, I only bought two more boxes after that to test the validity of that 2% drop rate. That, and see if I could get a Hood or some more Shadow accessories.
But unboxing the Wings on your first box? Mother of God.
3% is a fairly plausible number. It takes just under a hundred to be statistically certain that you'll receive something good for your troubles, and after purchasing any number you have a reasonable chance of getting a "rare" item; e.g. 10 boxes = 26% chance of encountering greatness.
I almost spat my drink out all over my computer when I saw I unboxed the Wings on my first (and only) box! Correlation doesn't exactly mean causation, but I do notice a lot of people I know have been getting really lucky.