"Their argument/story/point of view is not valid because they don't understand that you can just build things because you like building things" - 100% crowdpleaser. He is not addressing the issues, he is completely reframing it.
If you look for more examples check out the movie "Thank you for smoking": The question is not whether smoking is good or bad for you or whether we knew about that. The argument is whether we should make decisions for the people of this country or if it is their freedom to make their own decisions.
"What if..." is a sign of curiosity, exploration, creativity, imagination and a modest disregard for the risk.
- "What if I climb down that cliff... will I find a beautiful and isolated beach?" (Versus: fall to death)
- "What if I sail this ship a bit further? Will the next island be more bountiful than the last?" (Versus: crash on rocks)
- "What if I replace this diode with an LED? Will the effects circuit sound better?" (Versus: break the effects pedal)
And so on.
However, I wonder if all entrepreneurs are like he describes. In fact his description is almost at odds with what Zuckerberg said at Startup School, about simply building things because you like building things.
I think at the end of the day there's many motivations for doing something as bold as building a company, and everybody has a different mix of those motivations.