Just-Dice has a maximum profit of 80,000 CLAM. That's worth over 500 BTC at the current price.
80,000 CLAM isn't "worth" 500 BTC. I'm looking at the poloniex order books now, and it looks like if someone tried to sell even 5,000 of your site's play tokens it would drop the price over 80%. Now your 75,000 CLAMs are worth under 100 BTC. Funny how that works. But hey, never let "facts" get in the way of a good story

Most trading happens off the exchanges, as you well know. People don't leave their CLAMs idling in exchange orderbooks. CLAM is proof-of-stake, so they tend to be left somewhere that pays staking rewards. Like the JD bankroll for instance.
Note also I said "at the current price".