I'd say that anything with the word gamble in it is not safe. The only safe thing you could do is make sure if you are going to bet, only bet what you can afford to lose, and keep your odds of winning relatively high.
Indeed,don't be greedy cause no one will get rich because of greed. Most successful rich people comes from rugs to riches, they strive hard to get rich and I am pretty sure they don't get it from gambling. However, there are few exceptional people who made their fortune out from gambling. If you don't have that skills and knowledge then just treat gambling as an entertainment so you won't get addicted to it.