It seems every time (or 99% of the time) people gamble, they lose money. Why? Take a game like blackjack. The odds in a casino are something like three to one. That means, that on average you will win one out of three games. So if you just double or triple your bet each time, you will eventually gain.
Say you enter a casino with 10000 to spend. (I'm asuming you are rich, if you have less to spend, your initial bet must be less) You start my making a bet of $1. If you win, make the same bet again. If you lose, bet $2. If you win, restart at $1. If you lose, bet $4. If you win, restart at $1. Lose, and bet $8, etc.
The formula for the amount you bet would be: y(x^a), where y is your starting value, x is the amount of times you are multiplying your number by for each increase; if you are doubling, its 2, if you are tripling its 2, etc. A is the number of times until you win.
For example, in the example above, after 10 games it is 1(2^10) which means you have spent $1024. By this time, you will probably have already won.
Continue to increase your bet by double or more, and you are bound to win. If you start at $1, and have $10000 available for gambling, you can bet 13 times, by which time you should have won.
While it may take a long time to win, my point is that if you have enough money available, you will win no matter what. For a guy just spending his week's earnings, this is not a sound idea. However, for someone with billions of dollars, there can be no better way to increase your money by millions a day.
Why don't any incredibly rich people do this?