I've owned computers for a couple of decades. I was one of the first non-geeks on the internet. I've never had a virus that wasn't defeated by an anti-virus, I've never had a Windows crash that I lost anything and the only real trouble I've ever had was a dead motherboard- I popped the hard drive into a new computer and didn't miss a beat.
Since anti-virus software has been available, I've used it. Since firewalls were available, I've used them. There are basic things you can do to protect yourself- and I'm pretty much convinced that some basic common sense will prevent virtually all ad things, computer-wise.