A better way to estimate life expectancy is to use an actuarial life table. SSA has a very simple one based only on age[1]. Those show an expected 18 years for someone 65 years old. It's interesting to see that life expectancy stays above one year until the age of 113. Of course these are just expected averages, they are useful at scale but individual experience will vary.

1. https://www.ssa.gov/oact/STATS/table4c6.html