Your math doesn't check out. 5% of people that get it (among a wide range of ages) require serious medical care for weeks. And if we send 5% of any population to the hospital in a given month the death rate for ALL diseases goes way up.
The number of people that have it is under reported, so the death rate and hospitalization rates are exaggerated.
Just based on the experience in other countries, GP seems quite spot on in terms of who is impacted, who dies, and the percentage of the population. Your comment seems speculative and substantial number of non-70+ year olds dying has not been borne out by the data at all.