> honest question: what is the death rate for an average person in their 80s?

That's a standard actuarial problem, answered with life tables (https://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_03.pdf -- pdf, US 2008). In said life tables, there is a 7% death rate between ages 83 and 84.

To an order-of-magnitude approximation, infection with the novel coronavirus seems to impose roughly one year's worth of mortality risk on the victim.