Doing a little quick math, assuming in every sale Notch got 20 American dollars (Using 20 instead of the current price to give a more accurate number since the game was considerably cheaper in Alpha and Beta before it was fully released.) 9,000,000 times 20 = 180,000,000. Which is 180 MILLION dollars. Even if you cut that number in half for all his expenses, taxes, and margin of error assuming that a $20 average per sell made the total a little high, then Notch is still walking around with 90 million dollars and is still one DANG rich man. Plus that's not even counting the sales of the pocket edition or xbox edition.
All I can say is I have a lot of respect for Notch turning an idea for a game as simple as mining and crafting into a success. Then all the respect for the people at Mojang who took Minecraft and turned it into the multi-million dollar game that it is today. In my humble opinion, the world is just a little bit better because of Minecraft. Thanks Notch and congratulations on 9 million.