The company could very well still fail, and no matter how large they are their customers should never rely on their provider not failing to the point where they themselves will also fail if something drastic were to happen to their provider.

But that does not mean that a single individual can put themselves in the judge, jury and executioner role all at once without any kind of oversight, that's at best a misguided case of vigilantism and at worst an act that is disproportionate against innocent bystanders and possibly a far larger crime than whatever happened before.