They sound like they might be true, and people don't know how to check them out. They're not harmless pranks. Rosenberger said he knows of one case where a hapless computer user erased his hard drive because a hoax message promised to tap into his personal information and broadcast it via the Internet. That's an extreme case. But a lot of people waste a lot of time spreading these bogus warnings.
Resources cost money.
And, that's where you come in. Maybe you've never done this because you regard the fear of viruses as good for business. After all, you're always quick to send out alarmist press releases whenever a new virus comes out, reminding people about the importance of virus protection. It would save computer users a lot of angst.