I think that everyone understands this, even those who deeply believe in something supernatural. But the main goal of prayer is not to achieve a result due to something supernatural, but to achieve psychological calmness. This is important for those who play for big money and are worried about the result.
Yes, I agree prayer is both meditative and positive it enhances your mind to think clearly and calmly because your mindset is that you are guided to win, you are positive to win the game and you accept whatever results in it will bring you good or bad, I don't see anything wrong in praying while gambling I have seen a lot of lottery bettors here in our place who ask for guidance from the Almighty for lucky numbers and besides we honoring the existence of God.