> You don't think those who worked on the Manhattan Project knew the deadly potential of the atom bomb?

They did. I am talking about the physicists who preceded these particular physicists.

> And Communism didn't lead to famine - Soviet and Maoist policies did. Communism was immaterial to that.

The particular brand of agrarian communism and agricultural collectivization resulting from this subtype of communism did directly cause famine. The utopian revolutionaries did not predict this outcome before hand.

> People can easily point to how trains have done a net positive in the world and walk away from your argument thinking AI is going to do the same.

But that is one plausible outcome. Overall a net good, but with significant unintended consequences and high potential for misuse that is not easily predictable to people working on the technology today.