Did somebody in the room say, "We've crunched the numbers, and our best estimation is that if we orient all our resources toward achieving this goal and put forth our best possible effort, we'll be able reach 5x."
And then did somebody else in the room say, "I agree. So let's be extremely audacious and shoot for 10x"?
Either the first person was miscalculating or the second person was being unreasonable.
As per the spirit of parent's question - either you're assuming something impossible, or you're setting a goal to achieve something that is possible (in which case why haven't you scoped it out clearly & sanely).
It's a mix of product/tech knowledge, calculations upstream of how much Google needs from the YouTube business, and some savvy in understanding the people in the YouTube organization. Another mix of people in the same situation would probably come up with a different number, and neither would necessarily be wrong, or necessarily under- or over-analyzing relative to their capabilities.
Did somebody in the room say, "We've crunched the numbers, and our best estimation is that if we orient all our resources toward achieving this goal and put forth our best possible effort, we'll be able reach 5x."
And then did somebody else in the room say, "I agree. So let's be extremely audacious and shoot for 10x"?
Either the first person was miscalculating or the second person was being unreasonable.