Putting aside the deplorable ethics of freeloading in this matter, I think your analysis of the situation is objectively problematical. It is not plausible tha

Putting aside the deplorable ethics of freeloading in this matter, I think your analysis of the situation is objectively problematical. It is not plausible that, absent a vaccine or other cure, only a small percentage will contract it. The evidence strongly suggests that a large fraction of the population will end up catching it at some point. We already have plenty of evidence how that goes, in the chicken-pox outbreaks in the communities that have chosen not vaccinate, presenting a threat both to themselves and others. This virus is known to be much more dangerous. You seem to weigh your hypothetical problems of a vaccine much more heavily than the actual problems of the virus.