It is bad to expose other people to germs
Bob wakes up sick in the morning, he knows he has a cold today.
Bob wants to earn some money today.
Bob calls to tell his boss that he'll be working remotely today.
Bob goes to work sick and keeps working all day like any other day.
Bob gets out his laptop and works from home while sick to avoid getting his coworkers sick.
Bob gets all his coworkers sick and drops the company productivity to a crawl.