[H]ow are monopolies lost? Think about it. Some very good product people invent some very good products, and the company achieves a monopoly. 

But after that, the product people aren’t the ones that drive the company forward anymore. It’s the marketing guys or the ones who expand the business into Latin America or whatever. Because what’s the point of focusing on making the product even better when the only company you can take business from is yourself? 

So a different group of people start to move up. And who usually ends up running the show? The sales guy. John Akers at IBM (IBM ) is the consummate example. Then one day, the monopoly expires for whatever reason. But by then the best product people have left, or they’re no longer listened to.

Steve Jobs