Yes one bridge collapse a decade would be acceptable to me provided it keeps the cost down. Other people may be willing to pay for more nines, the point is that infinity nines costs infinity dollars.
You are ok with a bridge collapse every 10 years? Do you understand how rare bridge collapses are today and that this would be a massive increase in the rate of failure?
They were just giving their personal comfort threshold.
I mean, technically, one would need to look at the reliability-cost curve. opwieurposiu would almost certainly be fine with eight 9's of reliability if it only cost twice as much as three 9's. The fact that they have a really high risk tolerance in this area don't really undermine their general point.
If a person’s risk tolerance on something is out of whack of what almost everyone else is comfortable with then there is a problem with that position. At least as it pertains to public policy. I’ll rephrase and say that I hope OP is not in a position to have his/her views in this area become policy.