Having more money than you know what to do with is a sign that you've pretty much exhausted your growth potential. That's not quite the same as jumping the shark, especially if at that point you're the most valuable company in the world.

The correct thing to do is to start paying out dividends, and Apple has done that. Making a relatively small wild-ass investment vaguely related to their core business is at least a better thing to do with the other surplus money than going into finance or real estate.