it also makes it a whole lot easier if the company is on shaky ground and built up by hype, when everything does happen to implode in on itself. I'm not saying that this is airbnb's case but ...

I'm not saying twitter is a failure by any means, but none of the people that built the company are still there ( Jack Dorsey started square so maybe he is that small percentage of people that can juggle two amazing startups ). When all the founders cash out early, it just makes it questionable.