Actually a broken clock is never right, it's lucky 2 times per day.
I actually really like that quote for what is means.
Basically it means that if you claim something long enough eventually you will be right.
Sort of like the Cubs winning the World Series, if you say it will happen long enough, eventually you may be right.
Same with the stock market, if you claim it is going to tank long enough, eventually you will be right.
Right now I claim I am going to eat a sandwich, I should be right in about an hour or so.
~WC