Because if the number was 0.0005% you wouldn't see ICUs and morgues overwhelmed (why don't you calculate how many people that is for your country?)

And, again, that's my point: you're asking why it can't be a ridiculously small number when it should be obvious from the reality of the situation that it isn't!

Sorry, you make zero sense. First of all, not everywhere are ICUS and morgues overwhelmed. Some towns in Italy and Spain are hit bad, South Korea manages it without even having lockdowns.

Second, and that's my point: you can have the same result with two very different scenarios: either a lot of people have/had it but in the vast majority of the cases it goes without symptoms at all. So when a big part of the population gets infected only then you start noticing "ICUs being overwhelmed". The second scenario is: it causes serious problems for a substantial part of the infected so even the small number of those who got the virus will flood the hospitals.

And those two scenarios require different responses.

There was however a perfect environment which allowed us to have an idea of percentages:

https://www.eurosurveillance.org/content/10.2807/1560-7917.E...

And the percentage of really asymptotic cases is much lower than the most here expect.

All the tests in all the countries could be seen as the statistical sampling. The speed of the transmission is also known, and surely not fundamentally different than the speed of people needing hospital or dying -- the doubling time is nowhere faster than 2 days, and the typical is 3 days.

In short, it can't be expected that "already everybody has it" in the positive sense of "nothing will happen."

I mean, as of today, 0.018% of Italy is known to have died from COVID-19. 0.0096% of the world has tested positive so far.

So the true numbers are definitely higher than 0.0005%.