They don't "reimburse" anything. They only cancel the due amount. The only thing they lose is their wasted computing power (and some support costs) and I think

They don't "reimburse" anything. They only cancel the due amount. The only thing they lose is their wasted computing power (and some support costs) and I think the RAW computing power is very cheap to them, especially considering their scale. The cost in terms of support for the victims is probably bigger but still not significant.