i don't necessarily disagree, but your figures seem quite low.
>>The past week, there has been ~670 btc wagered on Betking. That is an expected profit of 6.7 btc/week, or $5,000 per week
my personal returns for the past 60 days was an average of 1.5 BTC per month, and i was about 1% of the bankroll. So i would guesstimate its about 35 BTC per week, not 6.7.