The Challenger died because the seals were too cold.
It was so cold on the launch pad that the rubber was too hard to make a good seal.
That is why EVERY ENGINEER involved wanted to suspend the launch until it was warmer.
MANAGMENT wanted the shuttle to be triumphantly in orbit when Reagan gave his State of the Union address.
MANAGMENT bullied the staff into being reasonable, and doing it THEIR WAY (or else!).
The rest is, as they say, History...
I really enjoyed the chapters in Richard Feynman’s books that talk about his investigation into the shuttle disaster.
It seems that the shuttle is about as safe as they can make it now - about a 1% chance of total loss per flight. That said, 1% can become %100 if the machines are put in situations they weren’t designed for.