I approve of this thread. 
I'd say that the million mark is moreso a buzzword for us internet forum goers than it is a measurment for success. I mean, we have games like the Iga Castlevania series that constantly sells ~350,000-400,000 and makes a healthy profit. And of course we also have other games like Heavenly Sword that sold over a million yet never saw a dime back.
It's crazy I tell ya simply crazy!
I wish video game development was more open like with movies, where the development costs are open for everyone to see. That would be awesome to see, so we could actually have a measurment of success for the game to reach.