That's not how epidemics work when they are contained quickly.
Europe has done a bad job at this.
Epidemics in the past have killed many times as many as the percentages above.
First, using the total population as a basis is just wrong. Some will certainly be immune to a certain degree while others are simply lucky.
Even very aggressive pandemics, hitting totally ill-prepared societies didn't infect every single person. Not even the black death managed to do so. So why do you think COVID-19 would end up doing that?
And using the 3.4% is another issue. Because you have the Wuhan rate, which is much higher than the rate eslewhere. And this thing is a moving target because testing was rather limted earlier. South Korea seems to be the best source to get mortalitiy rates due to their aggressive testing.
south korea is an outlier and most of their cases are not resolved, they may have a lot of false positives
time to act was weeks ago.
But ok, the source is your own calculations. Thanks for confirming.