A few weeks ago I read an article about the guy behind McAfee (yes, his name is McAfee aswell) who's going completely loco.
The strategy they used at the start was simply scaring people with worst case scenarios (read lies).
You can still see this strategy with the free ones like AVG. A few times a day you get these pop-ups like
"you ip address is visible to externals"
"some passwords are found on your system that are not encrypted"
"some processes slow down you computer" they always forget to list their own applications tho
all this is done to make you shit your pants and buy their "solving" solutions