Sears' downfall can be explained in game theory. Lock two in a room. If they cooperate, they get a reduced sentence. If one rats the other, one goes scot free and the other heads to jail. If both rat out, they get the max sentence.
Eddie's attitude is that everything is a zero sum game. Every department at Sears screws the other, fighting over the same pie. Instead of going the extra mile to satisfy customers, do the utmost to not bring them minimal service, because it takes away from profit. Sue vendors for not wanting to do business with you after you don't pay them. And Eddie set himself up as the arbiter of what does or doesn't get done. He micromanaged the company to lose money and customers at maximum efficiency.
There is no sentient being in creation who could have done worse, and no one who has distilled so much ill-will. No understanding of what every six year old retailer intuitively knows that goodwill just isn't a line item in accounting, it's a real asset with real effects that brings incredible returns. Customer goodwill is far more valuable than real estate, and investments in good will multiply over the size of your customer base. It's what built Sears into the largest employer in America. What iterative versions of the Prisoner's Dilemma teaches us is that you gain a reputation for betrayal, you break contracts, and you go out of the way to spread ill-will, you will reap the returns on that investment too, both in sentiment and profit.
Unlike the Prisoner's Dilemma, everyone knows who Eddie is, so there is only ill-will, and everyone wants to betray Eddie too, which we amply see on this board. Several of the people trashing him here are individuals few would expect at the highest levels, not limited to TransformCo, humorously key individuals he's been compensating handsomely for a long time.