Since Win 7, that's what most Windows virii are - 3rd party vulnerabilities and human stupidity....
Thats what I said
Human nature and a "Mac's don't get viruses" attitude goes a long way.....
I'm NOT talking about Macs I'm talking about computers in general. I get a constant stream of computers to repair (I was a component level service engineer 20 years ago but my normal charge for a repair now is booze so it keeps the drinks cabinet full

It's going to be a bottle of Gentleman Jim for the Dell which isn't bad because it's a £100+ repair) and more are Windows than MacOS (but you would expect that as more computers are windows).
At the moment I have 5 laptops here..... Macbook (6 years) old - Will not do anything at all {on/off button faulty, requires new top which is on order}, a Dell M5030 laptop (14 months old - beeps 7 times when you switch it on {requires me to take it apart remove the motherboard stick it in my SMD pre-heater and attack it with the SMD hot air re-work tool to reflow the CPU and probably GPU - it's a well known manufacturing fault with them}..... then 2 x laptops running Windows (1 XP & 1 W7) that have literally ground to a halt due to user's clicking anything they are told to click and them filling up with malware & another XP machine that Windows has imploded on! (I suspect malware on this one too but I've not even opened the bag yet as it was only delivered yesterday)
This is not a normal list and mostly I get few real repairs like the first two and more malware attacks most of which are Windows machines as MacOS is less susceptible BUT not completely immune (and more Windows machines exist).
Part of the "Apple is best" attitude is down to the fact that
on average it IS best because.......
IF you compare an Apple machine to a QUALITY Windows machine then there is less or no difference but most people go off and buy a £250-350 laptop from Tescos or PC world so it's hardly surprising that they are unreliable and build out of cheap plastic....
IF you compare a Macbook Air to say a Sony Vaio T then the Sony is slightly cheaper but in at the same sort of level(you don't get the Thunderbolt port but do get a normal HDMI) then they are built about the same. Neither is "better" than the other and it's really a choice of OS. There isn't really a massive price difference anymore when you compare like for like it's just that sometimes there just isn't a "like" to compare it with.
So basically if people stick to avoiding clicking on things on the internet because they tell them to, opening up emails that are clearly phishing, downloading hooky software and visiting very dodgy web sites then they will probably be ok. Installing a decent anti virus package is also a good idea but I still don't use one on MacOS.