I wouldn't call 1/3 "generous". https://covidestim.org/ https://covidestim.org/ has some estimates of the fraction of people ever infected by US state. I can'

I wouldn't call 1/3 "generous". https://covidestim.org/ https://covidestim.org/ has some estimates of the fraction of people ever infected by US state. I can't seem to find an US aggregate figure, but by clicking on a few random states they all seem to be at least 50%. California (the most populous state) is around 60% even before omicron. Your estimate is likely off by a factor of two.