The death rate is nowhere near 4%. The CDC estimated the infection fatality rate in the US at 0.6% back when almost no one was vaccinated. The vaccines and other improved treatments have now cut that risk way down.
Yes and the CFR in people 20 - 30 appears to be about 0.01% (very roughly).
Obviously some subpopulations are more or less vulnerable. Averaged over the whole population it generally comes to somewhat under 1%.
Check out the CFR for RSV (a common cold virus) or influenza in people over 80. Viruses that almost never incapacitate let alone kill healthy younger adults can often kill the medically weak.
Your own source shows quite clearly that the estimated death rate for >65yo lies between 3.8% and 4.0%.
The >65yo cohort is both the one reporting the lowest number of total infections (~18M) and the highest death count (~700k).