Hell, it killed around as many people as WWII, including the Holocaust (wikipedia estimates for WWII being >60million, and estimates for the Spanish flu being 50-100million.)
Numbers that big become very difficult to actually fathom in a meaningful way.
Killing about 5% of the entire population of the world about 100 million people, just imagine now with seven billion if a flu outbreak killed 350 million people.
Even people on remote islands in the middle of oceans died from the flu.
I hadn't heard about this so I looked up the primary reference[1]. I'm not sure that high aspirin regimens (the overmedication you're referring to) would explain the high mortality of the flu outside the U.S.
Further, the author of the study cautions that this is a correlation that could be important given our changed understanding of aspirin toxicity and not a proven finding.
There are (a few) people alive today who remember it.
It killed between 1.5 and 3 times as many people as the earlier WWI - but isn't as sexy as war, so hardly anyone studies it (relatively speaking)