Unfortunately once infected, that risk-taker will infect others and accelerate disease growth rate.

Infecting others who have no option to completely isolate or are just plain unlucky. Some of which will have possibly life-long lung damage. And some will die who would have otherwise survived.

Responsible people isolate, because they don't want to harm or worse, kill others.

It's not about living in fear. We're not quarantined because of fear. We're quarantined because of knowledge - we know how contagious this is, we know what the hospitalization rates are, we know our medical resources will be quickly depleted and we know how to slow the spread until we're better able to respond. The question we need to ask ourselves is why weren't we prepared?