this site is crazy, i lose all my coin in 12 round
What do you mean by 12 round? Is it 12 bets?
All money means how much?
It looks like he/she is referring to 12 rolls in the hi-low game. Many times many people already mentioned that this site has a very high house edge like 5% so you can't win money so easily. But if your playing with free money from the site then the amount is so small and due to high bankroll no way you can win it. If you want to try your luck then you should play on lower house edge site.
Playing on a lower house edge site only means that, on average, money lasts longer before losing it all. What usually happens in this site is that people get free satoshis in the free btc game and they spend those satoshis in the hi-low game.
There is no point in cashing them out to play in another site because of transaction fees, unless they wait for a long time before withdrawing but thats not what usually happen because people get too impatient. Its not a bad strategy, after all, if you only bet the free btc game earnings.