I'm following Martingale strategy which will be getting me profits only if I am extending my rolls; I mean even I am looking like out of control, I am still in control over my gambling and this way if I keep trying then I may get chances to recover my losses and also will get into profits. So, it is not only about when to stop but it is all about how you are approaching in calculated manner.
Gambling is based on pure luck, I agree. But, there are methods are available to maximize the chances for your lack factor to favor you.
The Martingale strategy is a garbage strategy that only serves to risk an increasing amount of money for a minimum profit that is less and less compared to what you bet as you lose and have to double the bet.
And no, gambling is not a matter of pure chance, it is a matter of mathematics, that you can not predict the results in the short term does not mean that it is not based on a mathematical certainty of the results in the long term.