> She figures that they’ve spent at least fifty thousand dollars in rental fees so far—more than they could get from selling the furniture.
That probably doesn't even consider inflation, $1 in 2006 was worth $1.60 in today's money. People are really bad at long term financial planning but also get really attached to objects with some sentimental value. So this is a market where it's even easier to exploit that poor financial education.
Even without the sentimental part, cancelling means sorting everything out and finding people to take it away.
In theory, one can just hand the keys to a Junk Busters-type company. But yeah - actually doing that is another barrier to action.
Rather than just not paying and letting the owner auction off the contents, maybe you can tell the owner of the storage facility you'd be fine with them auctioning off the contents without ever going into debt?