I don't actually think it is viable in the long run to be giving so much money away. Maybe smaller prizes, although iwon say they are doing alright I actually believe they are hurting. No one can give that large prizes away without hurting, and the only people that return day after day are gambling addicts, kids or people who don't have a lot of money to start with, not exactly top marketing demographics.
This is all assumption though as I have never seen their demographics, but I would not believe any collected by them, or any site.
It's easy to select that your household income is $100,000 a year. I mean, you are not exactly going to put $10000 if that was the case, and also it's easy to lie about your age.