That's surely how it would be represented in order to retroactively justify negligence.

But a more precise calculus would take into account that (1) the proliferation in ransomware is recent and explosive, and (2) getting hit by one ransomware group doesn't mean a second group won't strike soon. (Although I'm guessing the second wouldn't be allowed to use the same ransomware-as-a-service platform, as that would harm the platform's reputation.)