Yes, OK, some people have underlying health conditions and can choose whether to remain indoors or wear masks, but with regards to your claim that it does not explain why the majority of the population need to do so then if you can't even work that one out for yourself then I don't suppose you're ever going to understand the reasons why.

Coronavirus is a worldwide pandemic.  At present there is no cure for it, nor is there a vaccination widely available that can successfully prevent people from contracting the virus.

Cancer has been around for way longer than coronavirus.  Therefore it stands to reason that cancer has killed more people to date.  However, cancer does not spread from person to person by close contact, or by being coughed or sneezed upon by a person with the disease.  Coronavirus, however, can be transmitted to other people in this manner.  It can also be contracted by touching surfaces that a person with coronavirus has recently been in contact with.  I know of a person who became ill with coronavirus as a result of touching surfaces that had not been sterilised after a person who was found to have coronavirus had touched them, so I know that it can be spread in this way.

Have you actually known anybody who has been seriously ill with coronavirus?  I suspect not.  And it can certainly put people out of action for more than two weeks when they become seriously ill with it, often with side-effects lasting for several months afterwards.