I sell on other platforms that push hard for Black Friday sales, and I notice that the additional traffic leads to extra sales for me in certain category, even if my items aren't on sale.
A big problem that eBay has compared to say Amazon is that eBay is not a direct to consumer retailer. Amazon offers consumers both third party sellers, and their own items. This can be a bad thing because it means that third party sellers have to compete directly with Amazon, but when it comes to marketing for Black Friday it allows Amazon to drive a lot of traffic to the website because even if third party sellers with slim margins cannot mark down items, Amazon is willing to take a loss on things they sell like movies, video games, toys, etc to drive traffic to the website.
eBay also works differently. On sites like Amazon, everybody who wants to sell a Home Alone 2 DVD is pooled on the same listing. So Amazon driving people to a listing for an item on that they sell themselves and have on sale also brings attention to all the sellers selling on that same listing. With eBay, everybody who sells a Home Alone 2 DVD sells on their own listing. So it's more difficult for any one individual seller on eBay to drive people to their item.
I suspect that a lot of eBay sellers might see a drop in sales during Black Friday week, because even if places like Amazon, Wal-Mart, and Best Buy don't sell the same category of item as you, people only have a finite amount of money to spend. So while someone selling a niche item on eBay isn't directly competing with Amazon marking down a bunch of popular consumer items by 30-50 percent, because those markdowns are exclusive to this week people who have to choose between your niche item (which might still be there a month from now) and buying a bunch of items on their to buy list for half price, they are probably going to prioritize the stores with actual Black Friday sales.
