“Why would any healthy person want to take a drug designed to attack a disease they do not have?”
Try reading the real article from the LA Times- it explains it well.
As for your question- people who visit countries where malaria is endemic typically take antimalarial drugs. These drugs can have some bad side effects, and the people taking them do not have malaria. But can you understand why they take them?
People who are about to undergo surgery are often given antibiotics, even though they do not have an infection. But can you understand why they take them?
Those are two examples.