I see black Friday and holiday sales alike in two ways.
On the consumer side, I see it as a way for someone who wasn't quite ready to pull the trigger on an item to buy it, as it most likely discounted. This can be good in numerous ways; if it's a firearm purchase (especially a first time purchase) , well then that's another firearm in a responsible owners hand. Secondly, money for most is tough to come by. Who doesn't like to save some money? As for buying unnecessary items, well that's the consumers problem. I'm hoping retails still make money on every purchase, by no means should someone expect to pay less than cost no matter how good the deal is.
For the retailers? Well this can be tricky. With sales constantly happening, regardless of black Friday or not, that dilutes the value of a regular retail priced item. Why would anyone want to pay full price for an item when they know if they wait a month that item will be significantly less. This puts retailers in a tough spot, as they won't get sales unless that item is absolutely necessary, or the customer is impatient and want the item now. We live in an age where there is so much competition, the only way retailers (especially online) can get any attention is to run sales. If one retailer runs sales, well guess what, that forces the others to as well or else they won't get any business. I take it that's why MAP pricing exists. If a consumer knows that item will never go on sale, or the price is what it is, then of course they'll buy it at any given time.
That's just my take on it. As for me, I rarely buy anything at full retail price anymore as I know a sale or coupon code is right around the corner.