From Hacker News.
- We're going to build the next Facebook!
- We're going to found the next Apple!
- Our product will create sweeping political change! This will produce a major economic revolution in at least one country! (Seasteading would be change on this level if it worked; creating a new country successfully is around the same level of change as this.)
- Our product is the next nuclear weapon. You wouldn't want that in the wrong hands, would you?
- This is going to be the equivalent of the invention of electricity if it works out.
- We're going to make an IQ-enhancing drug and produce basic change in the human condition.
- We're going to build serious Drexler-class molecular nanotechnology.
- We're going to upload a human brain into a computer.
- We're going to build a recursively self-improving Artificial Intelligence.
- We think we've figured out how to hack into the computer our universe is running on.
This made me laugh, but from the look of it, I'd say there is little work to do to make it serious. Personally, I'd try to shorten it so it is punchier and more memorable.
9 has been done many times in human history too, for some reasonable definition of "create a better artificial optimizer."
Anyhow, to answer your question, I'm just guessing, based on calling "difficulty" something like marginal resources per rate of success. If you gave me 50 million dollars and said "make 2 happen," versus if you gave me 50 million dollars and said "make 9 happen," basically. Sure, someone is more likely to do 2 in the next few years than 9, ceteris paribus. But a lot more resources are on 2 (though there's a bit of a problem with this metric since 9 scales worse with resources than 2).
That's why 9 specifies "recursively self-improving", not "build a better optimizer", or even recursively improving optimizer. The computer counts for recursively improving, imho, it just needs some help, so it's not self-improving.