We oldtimers remembers a time when the Mac was tremendously virus-infested. You had to put some profylactic on your diskettes before inserting them, since you just knew they would be attacked by malware. Apple did a great job reengineer everything to solve that old mess. Alas, that have just lead to new fools buying the machines and inherriting the "I'm invulnerable" attitude.

In the end, all machines are (more or less) vulnerable. And the bigest vulnerability is normally sitting behind the keyboard, trusting everything that looks slick and wellproduced.