Most times people always pay deaf ears to their gambling dream. Most people has been given an opportunity in the dream to play certain game to succeed in life but they neglected it.
You are sounding like a spiritualist, what do you mean gambling dream?
Dreams are sometimes remnants of our thoughts, all the things that we thought about the most during the day, and then our subconscious minds dwell on it until it becomes a dream. Even If I see myself gambling in my dreams, I will still doubt the games, and will not be willing to stake a lot of money on these games. I have little believe for superstitions.
Well, not every dream is a remnant of our thought bud, real dream are real, while there's is definitely the dream that is a remnant of out thoughts, not believing in dreams is like not believing in the existence of God, for God even said in the Bible that He will sometimes reveal things to us through dreams.
Sorry, I don't mean to bring religion into the discussion, but to better drive my point home for clear and absolute understanding, I couldn't do without bringing in religion.
Though I highly doubt that op's story is true, I still will not deny the possibility of some persons getting a number to play, (most especially in the area of lotto) revealed to them in their dream, atleast, on one occasion, I've witness this happen to someone in my neighborhood, he wasn't a gambler but one day woke up and announced that he had a dream and some numbers were revealed to him, those who were gamblers decided to play that number in a lotto, as many of them that played it all won.