You do, though. Because although there’s a chance of catastrophic failure, the typical case is that the launch goes fine, and then they notice some unexpected degradation of the O-ring after the shuttle comes back. That’s how they were measuring chance of O-ring difficulties; a shuttle had never exploded, but there had been observable signs that things could have gone badly.

In other words, in most mechanical systems, a certain amount of wear and tear is acceptable. It’s only at extremes (way too cold) that it becomes a disaster. Convincing yourself that you’re certain there will be a disaster this time is a level of scientific and engineering confidence that’s hard to fathom.

In that situation I would have done everything possible to alert management that there was a high chance of an issue, but would I have grabbed my daughter and drove to stop the launch because I was 100% certain it would blow? Probably not.