Let's use some real numbers, shall we?

I looked at the CDC's website. I took their historic data, which for some reason stopped in 2015, and took their annual IFC numbers from that year as an average year (certainly, compared to 2020 it's going to look average). I combined all deaths from (1) pneumonia and (2) influenza, which the CDC has broken down by 10-year age groups except for under 5s and 85+.

Then I took the same CDC numbers for 2020 for (1) pneumonia (with or without Covid), (2) influenza (with or without Covid) and (3) all Covid cases counted by the CDC.

We can see, by taking 2015 numbers and comparing the combined death totals for 2020, the following data:

Age 2015 2020
Under 1 293 186
1-4 193 149
5-14 219 216
15-24 495 930
25-34 1033 3301
35-44 1884 7676
45-54 5801 19,745
55-64 13,795 50,533
65-74 23,251 87,200
75-84 36,774 109,827
85+ 56,074 125,701

But let's be thorough here. The 2020 numbers start at February 1 and run through December 9, so we should add 62 days and then multiply the 2020 numbers by 1.1694 just to be thorough (i.e., 62/366 + 1). I'm sure that will extrapolate higher than actual numbers, but we want to be as liberal as possible with these numbers.

The results I got were as follows:

Age 2015 2020 Adjusted Rate
Under 1 293 218 74.4% of 2015
1-4 193 174 90.2% of 2015
5-14 219 253 115.5% of 2015
15-24 495 1088 219.8% of 2015
25-34 1033 3860 373.7% of 2015
35-44 1884 8976 476.4% of 2015
45-54 5801 23,090 398.0% of 2015
55-64 13,795 59,093 428.4% of 2015
65-74 23,251 101,972 438.6% of 2015
75-84 36,774 128,432 349.2% of 2015
85+ 56,074 146,995 262.1% of 2015

Your anticipated 100,000 deaths for 50 and under doesn't pan out. We don't even get to half that by adding up to 54. Furthermore, the numbers are showing an excess mortality of approximately 3 times that of a normal year, which is precisely what I have been saying.

You're also seeing, interestingly enough, that the very young have an even lower mortality rate. This is probably because Covid doesn't really affect them, but the increased measures taken to prevent the spread of disease has made them less susceptible to "ordinary" infections.

Moreover, the vast majority of the deaths are in the over 65 crowd, and the over 75 are still well over half the deaths. This is in keeping with the 0.01% IFC rising to 0.4% by the 55-64 range, all the way to the 15% IFC for the 85+. Granted, even in a normal year they seem to have something like a 7% IFC from influenza and pneumonia given that the excess mortality percentage is lower.

Apologies on the failure of the site to render charts. The columns were nicely split when I typed this in.