Human error man, it’s poopie when it gets you.
But other than everything that’s been said.
(Such as dont fight the grade the graders verdict is final! accept it, Psa isnt perfect, it’s still a 9!)
How it affects me;
If i’m not happy with the card beneath the grade i just look for a replacement.
If you really want something and you got plenty of time left what’s stopping you from taking the journey?
If it’s the money just sell the one in your possesion 
I would actually recommend against selling it. When PSA has made a clear error, send it back to them and they will regrade it to the true grade that it should be. They then will reimburse you for the difference in market value between the grade that it originally had on the slab vs the new grade. I have done it with 4 or 5 cards or so. If you have an auction as proof of the price you paid, that will help a lot in establishing value and they can’t really argue it.
Simply send them an e-mail with your photo and a message indicating your desire to return it for coverage under their financial guarantee. They will even reimburse the cost you spent to ship it to them and regrade and ship it back to you for free. In my case, they gave me like a $80 voucher or whatever it was for discount off a future submission that covered the lost value in a few cards going from PSA 9 to PSA 4 and 6 (top right damage) as well as my cost in shipping it to them.
Very fair point in this case, i was speaking for myself though not his particular card!
Interesting to note @gottaketchumall , I had not known that. I certainly will look intoit. It seems very fair on all ends.
That’s those stickers and sticker style types for you.
I guess PSA wanted to be more inclusive in their hiring practices and hired someone who’s legally blind.