There was far more than a mistake that caused the Apollo 1 deaths. Their deaths was caused by a host of mistakes. First, the cabin hatch opened inward to save weight. Unfortunately, the instant the fire started, the internal pressure increased to the point where it was impossible to open the hatch. Ed White was an Olympic quality athlete. Had all three men been that strong, they still would not have been able to open that hatch. The pad crew tried to open the hatch but were driven back by the incredible heat. I seem to recall that it took over 40 minutes for them to get the hatch open.

Other mistakes included a host of known defects in the Block 1 Apollo capsule. It was a quality control nightmare. Add to that an excessive quantity of inflammable materials on the inside (including a lot of Velcro put there by the astronauts themselves) and materials that released toxic fumes when they burned. Then, throw in the ultimately major mistake of pressurizing the cabin with pure oxygen under high pressure and you have a bomb waiting to blow.

Individuals are free to make decisions including bad ones. The Apollo 1 astronauts did choose a dangerous profession and knew that going in. However, they also had to trust the appropriate government employees to make the right decisions. They paid for that mistake with their lives.