[Question] Was Eliezer Yudkowsky right to give himself 10% to succeed with HPMoR in 2010?

In Hero Licensing, Eliezer Yudkowsky states that in 2010, he would have given himself 10% chance of HPMoR being very successful.

He then goes on to explain why he thought that instead of something lower; but I don’t understand why he thought that instead of something higher: given that HPMoR did end up successful, it looks like it actually had higher than 10% chance of happening. Or maybe I’m by coincidence in the 1 in 10 worlds where it ended up successful? How can I tell?

If I try to use Bayes’s law: let’s call A “HPMoR is successful in 2022” and B “In 2010, there’s at most 10% chance that HPMoR will be successful”.
I want to update B based on A: P(B|A) = P(B)P(A|B)/​P(A)
P(A|B) = 10%, P(A) = ~1
So it appears 110 as likely that EY was correct in 2010 about his prediction now than it appeared then.

Is this calculation correct?

Obviously, I’m not that interested about this particular result. In general, how do I improve my own prediction-making based on evidence?