I agree that it's the number #1 reason that a person should use ad blocking. Not only are ads delivering malware but given how much of our lives and personal information pass through a browser the ads should be considered malware themselves.

However, is security the #1 reason that users choose to install them? Nah, they get installed because ads are annoying.

I say this as a cautionary tale, the most dangerous thing ad networks could do is clean up their act. If ads start being unobtrusive or native users wont be driven to install ad blockers while the rampant tracking and invasion of privacy continues in the background.