Good, then my isomorphism succeeded. Typically, people try to deny that the underlying logic is the same. Not in the way I think you think. They do? So if you agree that things like car or health or house insurance are irrational, did you run out and cancel every form of insurance you have and advise your family and friends to cancel their insurance too?

No, because we can quantify the risks and costs of those things and make good decisions about their worth.

In other words, if I assume that you intended that, for the sake of your argument, that we have the same amount of knowledge about insurance as we do about these existential risks, then the two arguments seem exactly as clever as each other: neither are terribly clever because they both point out that we need more information and well...duh. (However, see my argument about just how obvious "duh" things actually are.)

If I don't assume that you intended that, for the sake of your isomorphism, that we have the same amount of knowledge about insurance as we do about these existential risks, then the two arguments aren't so isomorphic.

But note that thinking climate change is a big enough risk to invest against has nothing at all to do with his little argument about 'oh there so so many risks what are we to do we can't consume insurance against them all'.

If this is the argument Cochrane is endorsing, I don't support it, but that's not exactly what I got out of his post. Lumifer's reading is closer to what I got.