I think that it is possible to make your argument even stronger: it took hundred thousand years to go from stone age to bronze age.
But is clear that "total intelligence" of humanity is different on any stage of its development, and when I spoke about hundred years, I thought of "total intelligence" of humanity on the level of 20 century.
Anyway in case of AI it is an analogy, and may not work. The AI problem could be extremely complex and even unsolvable, but we could not bet on it if we are going to be well prepared.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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