In 2001 Google didn't own YouTube. Today it does. YouTube profits from selling ads, that's true. Yes YouTube makes all of their money from selling ads. But i

In 2001 Google didn't own YouTube. Today it does. YouTube profits from selling ads, that's true. Yes YouTube makes all of their money from selling ads. But it's fate is highly independent from Google search. That's diversification. Same idea goes for Other Google businesses. As for Apple - it's less diversified than it seems: the fate of the watch, for example, is highly dependent on the fate of the iPhone.