It has been reported that Google's CFO induced the (gasp) "law of large numbers" to explain why the company's growth will inevitably slow. (See e.g. John Battelle's blog.) Such is the state of statistical education.
I think he meant to say "regression to the mean".
A typical use of the law of large numbers is to justify using random samples to make generalized statements about some larger population. It says that (under some assumptions) the uncertainty of these statements decrease with increasing sample size. I can't see the connection with declining revenues.