The biggest #1 threat is "LACK" of user awareness! PERIOD!! Yes all the others combined "are in fact relevant" BUT they all are part of user awareness or actually lack thereof!!!!
If, small word HUGE meaning, people were/ are aware of all the others threats than they should/ would be running some sort of anti virus/ anti malware and a very good fire wall at the very least.
Now, couple that with a dose of common sense, don't just blindly click on links, don't just blindly provide user information at the drop of the hat, etc., etc., etc.!!!!! "All of this, IMHO, falls under "Lack of User Awareness"! PERIOD!!
I've talked to people, my own son included, that said "I've been had/ infected or whats wrong with my computer, etc." to find out that, "IF" in fact they had any anti what so ever, it was totally out of date(two or more years old) or they hadn't updated the signatures for months and had NOT scanned their computer for threats! EVER!
The internet is /was/ has become, much akin, to the worst street in the baddest part of any town in the world. Would you walk down that street if you didn't have to?? Anymore anytime one logs on to the internet that is exactly where you are whether you realize it or not! If you had to walk that street, I'm sure you'd feel much safer if you were armed or had an armed guard escorting you. Yet some people log on to that street with nary a care in the world! No protection what so ever!!!!! No anti virus, no anti malware, no firewall! God it's grand to be naive!
Now some of the responses so far are saying it's Windows/ Windoze fault. To that my response is "BULL S#!T!!!!!!! If you think your Apple or Linux OS is "Totally, 100% Secure", your living in a dream world!!!! There is "NO 100%, TOTALLY SECURE OS"!!! PERIOD!!!!
Maybe they haven't targeted you yet but keep bragging. Apple did and got hit with, I believe, 2 pretty impressive attacks with in a couple of months! Keep flapping your yaps!! Maybe then some of the heat will be off Windows for a change!
I, personally, run Norton Internet Security 2012. I won't claim/ brag that it is the best but it has less system impact than Norton 360! It has a firewall, anti virus/ anti spam. Along with that I've installed Malwarebytes Anti-malware free, only drawback is manual updates and scanning but it works! Also Secunia PSI to stay on top of all security updates. If that isn't/ wasn't enough, I've installed File Hippo Update checker and CNet TechTracker to insure "All My Programs" are up to date! Oh, btw, I'm running Windows 7.
Am I paranoid??? I don't think so! But I'm cautious AND keenly aware of "Security Threats!!!!" Remember, the data, computer and personal information you protect IS YOURS AND YOURS ALONE!!
The internet is chock full of villains, evil doers, hackers, and ID thief's. As, I believe, Ben Franklin said;" An ounce of prevention is better a pound of cure." Truer words were never spoken! Anything, free or bought, is much better than absolutely nothing at all! Some are better then others but hands down absolutely beats nothing!
You wouldn't leave your home with the front door unlocked/ open would you???? Why would you not try to lock/ secure your computer/ data?????