I personally think he has made a HUGE mistake turning this down. As the article points out, it is hard to see how Snapchat can even make money, and I don't think his potential demographic is anywhere near as big as Instagram's (Facebook purchase) or Tumblr's (Yahoo purchase).
It's gone to his head. He is my age and looking at something he made with his own hands blow up in his face. He is riding high on adrenaline and loving it and blind to everything but the upward growth on the prediction graph. That graph is telling him that he will be twice or four times as big this time next year. What he fails to see is how fast and hard the app can (and will) fall when the next cool thing comes along. Apps like these are fads. They are not sustainable in terms of growth once they hit mainstream because the fact that they are a cool little in-secret is half of the appeal to the teenage demographic. I seriously doubt he expects that he can make 3bn out of revenues from it, I think he's just hoping to sell for 10bn next year. Or it's his baby and he doesn't want to give it up to Facebook to watch it be destroyed. Regardless, 3bn is 3bn. Open your eyes man!
It's insane what you can do with 3 billions dollars. You could buy out more than half of the companies in a small city and monopolize them., You could build the largest building in the world with one room, make it your office just for the hell of it and still have 2 billions dollars left. Turn down that kind of money? The guy is clearly blinded by greed.