Be that as it may, federal law does not require sick leave [0], so expecting people to act against their own interests is not the clear solution.
The dilemma between
- your livelihood & potential (costly) treatment
- absence without sick pay
goes beyond kindergarten-level because kindergarteners really don't have much to lose.
Staying at home when you are sick, from the employer's perspective, should be vastly preferable. Even if the employer were totally heartless about people's health and only cared about money, it's a risk avoidance strategy that pays for itself many times over by reducing the chance the business collapses. They lose a negligible amount of productivity to reduce the risk they lose a significant amount of productivity. And yet, there are many employers who will hold you in contempt for asking they institute sick leave -- even if it's the only reasonable way to deal with the reality that people transfer sickness but also need to eat.
Sick people act rationally when looking out for their own livelihood's continued existence. I agree it's definitely good to hope to gain recognition for your displays of respect towards your employer/coworkers. But if your employer/coworkers do not respect that you have jeopardized your livelihood for their benefit, the continued and self-inflicted cost is pretty much a total refutation of "good breeding", cultural learnings, or understanding what manners are for.
And then, beyond the 1st-order consequences, there are 2nd-order (immunity/interpersonal/office politics) consequences of the decision to prevent people from coming into contact with all pathogens, if the primary aim is only to reduce the risk of extremely harmful pathogens (but those aren't particularly relevant to the discussion of individual decision-making).
[0] https://www.dol.gov/general/topic/benefits-leave/sickleave