The life expectancy at birth in the US in 1950 was 68.2. Since that was 70 years ago, more than half the babies born in 1950 should have died by now. I doubt that is correct.
that number fails because it cannot predict medical advancements in the future, when they occur, and how they will benefit those currently alove, whether or not they can get them, when they become mainstream care procedures or drugs, etc...
needless to say as advancements continue those older life expectancy estimates get more and more inaccurate