It's not about preaching that you can't win, it's the risk and the element of luck behind your bet. Just like in lottery, picking the 6 or 7 or 8 numbers, you need to be very lucky.
What can you say about this? Are you willing to risk your $18 to win $18k, or a million in PHP pesos?
The question is, do you think that the person that won $18k will simply stop gambling and believed that he can continue with his luck since he tasted that big win? What will happen if he experienced that bad luck? Believed me, he will comeback and play again and again and until that money is back to $18.
Seen worst, winner jackpot in the casinos, $100,000 but in matter of months, he "donated" it back to the casino that he won that big money.