I could be more forgiving to NASA if a propulsion system had caused fatalities with Gemini than I can overlook the loss of Apollo I and Challenger - both of those are simply unforgiveable.
FFS, a pure O2 environment? Everything is flammable then.
The engineers told NASA temps had been too low for Challenger to launch and they went ahead anyway.
Fuck all the asshats involved in those decisions - you killed 15 people.