Paranoia rules in the internet arena. There is only one sure defence, common sense.
Most of the problems encountered by people are from clicking on links in unsolicited emails and on dubious sites or, by falling for the basic email scams.
I've surfed the internet arena for many years, including some of the dark side, with basic precautions. I run FF (Latest update installed), Avast, free anti virus. Comodo, free firewall and Spyware Terminator. The only other security is through my Wireless router.
I have never had a virus, Very few Trojans and my bank still has all (not a lot) of my money in it.
If it can be designed by man it can be hacked by man. What is comforting (to a degree) is the fact that these days the browser people try to stay atop of it all.
Oh yes, I forgot to mention, I enjoy surfing with FF. Having tried all the others I keep coming back...