When to doubt
If Steve Jobs would have asked industry experts before launching the iPod, they would all tell him that entering the mp3 player market is a waste of time and effort; market was already saturated with cheap players, some as cheap as $10. The differentiation was low (what can possibly be different about a device that plays music?) and the focus was in making devices really small, or increasing the capacity. Mp3 players already could hold more songs than a standard CD player and thus it seemed there was nothing left to innovate. Coming out with a premium music player was a bad idea.