It is because stores sell more stuff on that day. They are in the black,( color of ink that used to be used to denote profits) instead of the red ( ink that denotes loss) it’s important to understand that Black Friday started in America as a business strategy in the 1950’s and exploded into a frenetic spending day. It took a few decades before it took over the holidays here. And online shopping and mass chaos of ridiculous hours that stores opened for Black Friday are sounding the death knoll.