You estimate the government might press ahead even with 9% probability of extinction. If every competing government takes on a different risk of this magnitude - perhaps a risk of their own personal failure that is really independent of competitors, as with the risk of releasing an AI that turns out to be Unfriendly - then with 10 such projects we have 90% total probability of the extinction of all life.

Um, hypothetically, once the first SIAI is released (Friendly or not) it isn't going to give the next group a go.

Only the odds on the first one to be released matter, so they can't multiply to a 90% risk.

</nitpick>

With that said, you're right that it would be a good thing for governments to take existential risks seriously, just like it would be a good thing for pretty much everyone to take them seriously, ya?