Then explain the Apollo program, and the actual printed literature that came out of the program that summarized how they were successful.
Apollo killed three astronauts. NASA learned some lessons from that and the rest of the program was safer, although still extremely risky.
If you're looking for programs where mistakes were not made, Apollo is not the program to choose. I highly recommend visiting Kennedy Space Center some time where they go in-depth on how close it came to never happening after Apollo I. https://en.wikipedia.org/wiki/Apollo_1
That being said, I'm a big proponent of "you can't make ICBM's carrying humans 100% safe", but you sure can try your best.