You really can't lose and there is no catch. Even if you don't win a prize on a given day or week, your funds are still available to you at all times at your discretion. As long as your funds are in the account, you have the chance to win prizes every day.

The reason is, that prizes are powered by the interest generated on all crypto in the draw. This way, as long as there is crypto in the draw, there will always be prizes paid out. And only the interest generated is powering the prizes, not the deposits itself. Therefore, it is called a no-loss draw.