This was my hypothesis when faced with the varying extreme cases.
And, it seems logical that a disease that effects the repository system would hit those harder, who's lungs are already working extra from the environmental pollution.

I am unsure about China's numbers. Basically, at some point they just stopped reporting,
or the CCP just stopped testing,
or everyone was soooo scared, that going to the hospital would mean their family might be welded into their apartment.

The only stick in this ointment is smokers.
Smokers who are usually known for getting respiratory ailments worse... are seemingly more immune.
But, that seems to be taken care of by the study that tobacco smoke is taking up the receptors that the Wuhan-flu would attack.