You are treating "investing in preventing X" as the same thing as "insuring against X." They are not the same thing. And they are doubly not the same thing on a society-wide level.
Insurance typically functions to distribute risk, not reduce it. If I get insurance against a house fire, my house is just as likely to burn down as it was before. However, the risk of a house fire is now shared between me and the insurance company. As Lumifer points out, trying to make your house fire-proof (or prevent any of the other risks you list) really would be ruinously expensive.
For threats to civilisation as a whole, there is no-one outside of the planet with whom we can share the risk. Therefore it is not sensible to talk about insurance for them, except in a metaphorical sense.
You are treating "investing in preventing X" as the same thing as "insuring against X." They are not the same thing. And they are doubly not the same thing on a society-wide level.
Fair enough, certainly one can draw a distinction between spreading risks around and reducing risks; even though in practice, the distinction is a bit muddled inasmuch as insurance companies invest heavily in reducing net risk by fighting moral hazard, funding prevention research, establishing industry-wide codes, withholding insurance unless best-practices...
The finance professor John Cochrane recently posted an interesting blog post. The piece is about existential risk in the context of global warming, but it is really a discussion of existential risk generally; many of his points are highly relevant to AI risk.
He also points out that the threat from global warming has a negative beta - i.e. higher future growth rates are likely to be associated with greater risk of global warming, but also the richer our descendants will be. This means both that they will be more able to cope with the threat, and that the damage is less important from a utilitarian point of view. Attempting to stop global warming therefore has positive beta, and therefore requires higher rates of return than simple time-discounting.
It strikes me that this argument applies equally to AI risk, as fruitful artificial intelligence research is likely to be associated with higher economic growth. Moreover:
So should we close down MIRI and invest the funds in an index tracker?
The full post can be found here.