If it starts worrying more than astronomers do, sure. The few is as in percentile, at same level of the worry.
More generally, if the degree of the belief is negatively correlated with achievements in relevant areas of expertise, then the extreme forms of belief are very likely false. (And just in case: comparing to Galileo is cherry picking. For each Galileo there's a ton of cranks)
Why does SI/LW focus so much on AI-FOOM disaster, with apparently much less concern for things like
Why, for example, is lukeprog's strategy sequence titled "AI Risk and Opportunity", instead of "The Singularity, Risks and Opportunities"? Doesn't it seem strange to assume that both the risks and opportunities must be AI related, before the analysis even begins? Given our current state of knowledge, I don't see how we can make such conclusions with any confidence even after a thorough analysis.
SI/LW sometimes gives the impression of being a doomsday cult, and it would help if we didn't concentrate so much on a particular doomsday scenario. (Are there any doomsday cults that say "doom is probably coming, we're not sure how but here are some likely possibilities"?)