Nice detective work. I didn't pay close attention, but am happy to believe that you made sure everything checks out.

The whale investor effectively has 3949 BTC in the bankroll. He keeps most of it under his own control, but risks as if he had the whole amount invested. If a whale player comes along and wins a bunch, the whale investor quickly loses his whole deposit. That's why he gets the lion's share of the profits.

You can go back through the old "JD Investor" thread and see us discussing exactly this situation. I ended up not allowing investors to use leverage like this, because I was concerned it would allow rich investors to dominate the bankroll without taking on the accompanying counterparty risk. When the small investors figure out they're getting a poor deal, they'll either pull out, or increase their leverage too (I was imagining that would be a feature available to all, not just those with >100 BTC) - neither of which is good for them.

As for whether it's silly, I guess the site is happy, because they can say "we have the biggest max profit of any BTC dice site", and I expect the whale investor is happy, because he's getting most of the profits. The only people who might not be happy are the smaller investors. But I guess the site can do without those anyway?