I'd be willing to say that majority of profits came from WAY before dividends were a thing, for example I had 2.5 million volume before dividends were implemented. I know other players like @lexilee around the same volume and @lisboa and @grandlisboa had much more than me from BEFORE dividends were implemented. Just from us 4, statistically they should have made at least 100,000 STEEM before dividends were implemented. There were also a 3 or 4 big token farmers before dividends were out that had around 10-50 million tokens so around a few hundred thousand volume each. This accounts for around 110,000 STEEM just from 8 players from before dividends were out and I'm sure there are people I'm forgetting with large holdings. Assuming let's say all the other players combined lost 10k STEEM before dividends started, that's a total of at least 120k steem earned before dividends started.

However, that means their earned amount is still above 70%. This makes a lot of sense as most of their profits come from blackjack I assume, since players don't play perfectly so the real house edge might be as high as 10% (random guess) against players who just aren't good. Remember, the house edge is 0.5% on blackjack ONLY if you play perfectly, like a bot.