..and if you are going to clean your toilet how many hazmat suits do you wear?
For me its balance of convenience over security, leaning towards the convenience side.
If flash and other crap is up to date , and browser , then i'm probly ok.
I suspect the majority of crap gets on computers because people AGREE to install it.
They try to download , say , a driver . For reason only a user could explain they have ended up at "drivers-R-Us" rather than HP.com and when the they click the GIANT green button that says "FREE DOWNLOAD of your stuff , plus good karma forever" , they arnt in the least phased then the download dialogue box asks if theyd like to run "Downloadmanager.exe" rather than "printerdriver.zip"
If people just check wether the type of file they are getting matches what they want , and pay attention to where its coming from everything would be ok.
(ok 0 day drive bys not covered in my sucurity policy , but i dont constantltly cruise the sort of sites theyd be set up at and rely on not being the first victim)