There is when they keep refunding people for having their account hijacked and on the other end are giving away CPU resources to the bitcoin miners.
Here's a hypothetical, what is the real cost, he said they were using spot instances too. A huge spike in demand might have an effect on price, pushing the cost up for all legitimate users. As far as the reserved instances, they were there, not being used presumably. They don't really lose anything except possibly some electricity and bandwidth costs?
When people run up a huge bill and don't pay it, that's an incentive.
The profit margin on AWS is stupid high. It costs Amazon nothing but power and opportunity cost to refund unintended use.
What about the potential customers they lose?
Side question: is there any similar cloud service with hard billing caps?
I'd really love to know. Because if I could get AWS-like service with the ability to have it cut off if my bill gets to say... three times my usual monthly... That'd be worth switching for the peace of mind.