It is called "Black Friday" because the large volume of sales allows the retailers to put their books "into the black". It has nothing to do with race.
I have been a retailer (a line of work I can't recommend, though it can be very profitable, and free of corporate politics if your sales figures are good enough) and I can tell you that some customers are so thirsty for a good deal that they will go to outlandish lengths to get it. Sometimes, marginated customers (of all races) will desperately hold out hope that they can qualify for credit or otherwise be able to afford the desired item.
And there are just some people for whom the combination of money and consumer goods becomes a recipe for "instant @**hole". Every aberrant, dysfunctional behavior imaginable can be encountered if you stay in retail long enough.