Actually, there are two reasons something doesn't sell.
First and foremost, it wasn't advertised widely enough and described well enough. One short craigslist with no photos won't always git 'er done.
Second, the asking price is too high and/or the market for the item didn't move the way you hoped.
The DE tool box is akin to those who bought commemorative edition Corvettes or the last Cadillac Eldorado convertibles and sealed them in plastic bags. Twenty-thirty-forty years later, with inflation and lost opportunity cost of the money, plus giving it storage, they're taking a huge loss.
There's one on eBay for $11,000 and he'll have it there a good long while.
jack vines