It’s the contagious nature of COVID. It might not kill 9 people out of 10 but it will spread to 100 people quick. Then it will kill 10 while 200 are spreading it. Do you get the picture?
First of all, R0 can only be measured with accuracy after the fact. Any posturing about what it is now is speculative, and FWIW your estimate of 10 is akin to mumps and chicken pox and beyond any known R0 estimate in the US by a wild multiple.
As for your 10% case fatality rate - you are waaaaay off for the nation as a whole. That CFR is possibly close to that for 80+ year olds. But not for the general public.
COVID19 is a highly contagious bug that can be nasty for many people and is fatal especially for the elderly and those with comorbidities. But as of this morning, we've had 10MM cases (not all of which are symptomatic) and 242k fatalities or a 0.242% case fatality rate. That's higher than the 0.1% CFR for influenza (where the vaccine has ranged from 20-60% effective in recent years) but it's not Ebola.
To suggest that normal, healthy people get the COVID19 vaccine is like suggesting that senior citizen woman take the pill to avoid pregnancy.
But what if I want you to die?