Commonly the 1 unhappy customer might tell his story to ten of their friends or thousands+ of readers online. Fixing customer problems (especially drastic ones) carries large incentives, because those single stories will actually be observed, while the 1000 happy customers won‘t be mentioned.
The company will only fix problems for customers with sufficient social reach in that case.
Case in point:
20 years ago DHL told me the credit cards I was waiting for in Santa Cruz, California were suddenly in transit to South Korea.
As a one off it was a funny story. 10 years later they told me the computer that was sitting in a depot in London was on a ship back to the US.
I'll keep telling those stories until everyone involved had long since retired.
To answer the question in the plainest way: the possible revenue potential from the unhappy customer if turned to a satisfied recurring customer.
This is really just a question of the opportunity cost, which can vary.
The depressing bit is that they can make a rational decision to weigh that cost against the amount of money it takes to keep people happy (vs doing nothing). Not that I support it, but they might be following the financially superior option. There's a lot of incentive to get that answer "correct", so I suspect it's currently working out in their favour, even though it sucks for those of us caught on the shitty side of that equation.
While true that economies in their various forms can form unsympathetic relationships between producers and consumers, it seems that, broadly speaking, producers who align more strongly with consumer satisfaction tend to ‘win’ and those who broadly speaking don’t tend to ‘lose’ on a long-term basis.
To their credit, Apple seems to get this mostly right.
Not being facetious, just pointing out the depressing nature of our reality. :/