A few questions about sick days?

My wife and I get into this discussion all the time. I say paid sick days are part of her employee benefits and if she doesn’t use them she is basically throwing money away; they are gone at the end of the year and do not accumulate. She says they are there “in case” something happens; therefore, she should do everything she can not to use them.

It’s not like I tell her to take a fun day, it’s just that she does get sick and exhausted and she is always so fearful to take a day off, as if she will get in trouble.

What do ya’ll think? Is a sick day a benefit or a safety net? How do you use your sick days?