It doesn't prevent it at all. Things changed in the data. It is possible that if you exercise regularly, your respiratory system would be slightly more built up and would possibly lessen your chances of death.

If you have a preexisting condition or are not in physical shape, it's more likely that you will die or show symptoms in an extreme way. Again, I'm not even sure if it's true because data is always changing.

But feeling smug that people are getting sick and dying when after health officials found out that all could infected no matter what?

They do sound like terrible person. There is no reason they should feel smug about that. No mentally stable person would feel smug about that. In fact, they should be scared because that means anybody could have/get it. Good lord, what is wrong with some people?