You don't have to believe me. I'm only relaying what is the currently accepted scientific understanding, that so far we've only treated the symptoms of aging, not increased the potential for longevity.
"The U.S. Census Bureau view on the future of longevity is that life expectancy in the United States will be in the mid-80s by 2050 (up from 77.85 in 2006) and will top out eventually in the low 90s, barring major scientific advances that can change the rate of human aging itself, as opposed to merely treating the effects of aging as is done today." (emphasis mine)
https://en.wikipedia.org/wiki/Longevity
> surely you're not suggesting that longevity decreased on average between 1920-2000?
You've completely lost me here. This is a straw man argument, I didn't say a thing about what happened to longevity this century, and the data clearly shows it has gone up slightly. Experts agree it will reach an asymptotic peak unless some science magic happens. But no science magic has yet happened, and while I agree we should pursue it, we have no scientific reasons to suspect that it will aside from human curiosity, desire to live longer, and fear of death.
> Kurzweil is overly optimistic about these things
Now that's just funny. There's a world of difference between being optimistic and overtly lying to prove a point that doesn't exist.