Even so, of you assume that average person knows 20k words but would only use about 2,000 words in day to day life, and thus in his or her password. That still

Even so, of you assume that average person knows 20k words but would only use about 2,000 words in day to day life, and thus in his or her password. That still means that at one billion passwords per second (which is completely unrealistic, unless you are NSA) it would take 1.8 years to crack the password. Who would invest that much time and electricity into a wifi password, unless, again, you are the NSA :)