You're welcome to try it, but consider that to cover eight losses, you need a bankroll of $255 to win ONE DOLLAR! Below is a chart I got from
http://wizardofodds.com/gambling/scam.html of how the martingale system works over a theoretical one million trials.
Sure, the red peak on the right hand side is mighty tempting, but the smaller red rise on the left still indicates a net loss with this system.