I don't track the exact amount, but I'm just outside the Top 60 with my city.

Most cards go for much more than 30 SIM on the market. In fact, I believe people can actually make a profit (on average) when buying cards from packs and selling them on the market. For instance, @desyfit has been doing that quite frequently, and I'm sure they wouldn't do that if there was no profit in it.

In regards to your last sentence, there are two things: (1) I think DCity turned around about $700k from card purchases, but most of that has been handed back to the players through SIM that has been recycled in payouts. (2) You clearly don't like the game, and it's fine to sell your city and use the Hive to play a different game. But as I mentioned in my previous post, it is not correct to call it a scam.