47 infected messages last night, 72 this morning, plus quite a few that looked like the virus messages but had no attachment (probably cleaned somewhere along the way) so they made it to my inbox and useful postmaster "Hey, you might have a virus!" email messages.
Spam exists because it works, some small fraction of the population buys what they're selling.
Viruses work because people click on attachments sent to them by strangers and don't apply software patches to their lousy operating systems. Software patches often aren't immediately applied because they might cause more problems than they solve.