No. Let's say you are really good at this game.
You take away your 1000BTC investment. Now you use your gambling skills to win back all the other investments with your 1000BTC. You know have, let's say, 2000BTC.
You now own the entire bankroll. You invest it all. Congratulations. You own all the site's money.
well, if you can "use your skills" to win 1000 BTC (having only 1000BTC to begin with), then you can just go on and become infinitely rich.