This really is picking and choosing specific technological examples rather than looking at the overall pattern. In 1964, five years before the first moon landing, it looked a few years off but certainly not a hundred years off.

I don't think Eliezer meant to say that breakthrough technologies always seem 50 years off or impossible until they are invented. Those who were paying attention to computer chess could predict it passing the human level before the end of the millenium, and we've seen self-driving cars coming for a while now. Anyway, I've added a clarifying note below the Eliezer quote, now.