It’s the opposite really - even if you have really safe parts, the overall system will be more likely to fail than any particular part. Say you have 10 indepen

It’s the opposite really - even if you have really safe parts, the overall system will be more likely to fail than any particular part. Say you have 10 independent critical components each with a 0.99 probability of not failing. Well the probability of nothing failing in the system is 0.99^10 ≈ 0.9. So your collection of parts each with a 1% chance of failure has a 10% chance of some critical component failing overall. Of course it’s more complicated because in real life nothing is really independent, and failure of one component will be coupled to failure in another. This makes simple solutions like redundancy not necessarily helpful (and sometimes even detrimental).