What's the cite for that number? I'd be very suspicious of anything claiming a 5-significant-figure result in a disease that has only (heh) 3M known cases.
In fact there's significant supposition that the incubation time and asymptomatic contagious state can last much longer than originally guessed. This would go a long way to explaining the difficulty of detecting early outbreaks (basically nowhere in the world was able to contain before community spread was happening) and the anomalously low rate of new case decline post-peak. But there's no good science on this, and probably won't be in time for it to be useful.
You are totally right about that. I misinterpreted the following paper https://www.ncbi.nlm.nih.gov/pubmed/32150748
The actual number is more like 1/100. The 1/10000 number is the probability for someone who has a 1/100 chance of being infected to develop symptoms after 14 days.
Uhm... too late to fix my original post, sorry.
Also, the number I have seen was ~1% of cases where asymptotic for 14 days. https://hub.jhu.edu/2020/03/09/coronavirus-incubation-period...
Something else is driving those numbers, and it ain't the actual number of new infections. For me the obvious candidate is they hits some testing limit.
Although it's also most certainly true that we're vastly undercounting the cases in most (if not all) areas.
The most common fatal case seems to be roughly: 1 week without symptoms, 1 week of mild symptoms, 1 week of severe symptoms, death. That's 3 weeks.
In rare (1/10000) cases, incubation time can reach 14 days, that's where the 14 days quarantine recommendation comes from. But the median is closer to 5 days.
Time to death can be much longer, the virus can cause all sorts of damage to the body, including secondary infections. And if the patient is strong enough to resist the primary infection but not enough to recover, it can take a long time.