[jleader]

The difference is that if NASA screws up, there's a certain percentage chance that the bug will be exposed, and cause a problem. That percentage usually stays constant over the lifetime of the system, regardless of how many times the bug has already bitten them. In an adversarial situation, there's a percentage chance that the bug will be exposed, and after that a 100% chance that adversaries will exploit it.

[mmsmatt]

Pick up "Capital Markets for Quantitative Professionals" - a great resource - and get a taste of this as early as the preface! The author writes about a bug he introduced in a program making markets in treasuries. It cost his firm $30k every trade, and the errant trades piled up as other participants recognized his mistake.