There are allot of people who got rich by gambling but are they still rich. There are more people who could say to you that you dont must go to gamble. There more people who got rich and gambles everything away so look further without gambling your life would be many times better.
I don't see or heard that someone got rich of gambling only now as you said. Many rich people who gambles got broke rather staying rich because all we know that gambling will destroy your life if you are addicted to it. Many people said what you said but the decision is still on yours not on them so whatever they said if you follow them then its your choice so make sure you are in the right way.
I think if there are some people who got rich accidentally with gambling then they won't allow the people to know it. They will just keep it as secret. And I think if they are going to become rich in gambling and they keep on gambling then they are not going to think about their money even they are going to lose it again.
It's not accidental because in the first place they aim to make money in gambling, maybe you can call them lucky but that is not incidental. If I am in the situation also, I would not bother telling people that gambling made me rich, and there's nothing to brag about if you can enjoy the winnings you have by yourself. Letting the others know is just like telling, hey!! Rob me.