As gambling games are based on random, independent events, betting systems cannot make a steady guarantee on what the outcome might be. When you flip a coin, the chances of you getting either side would be 50-50. But the situation is even more complicated in online betting. For example, for every 18 even money options that you choose in single-zero online Roulette, there are 19 options that might make you lose. Even in Craps, if you choose to go with Pass or Don't Pass, you can find yourself around 69 ways to win while chances of losing will be 70. Different games will have different winning and losing options, but in any case the chances of winning and losing are not equally divided.
Many losses may lead to a win
Basically, in gambling, there is no steady rule that you have to keep on winning if you want to make big money. Even if you have lost the whole day, your chance of that winning strike could be the next hand! So basically, it doesn't matter even if you have lost the whole day, doesn't matter if you bet only $5 in your previous game, it doesn't matter if you played at a different table last. It all boils down to what happens next.
Cards are drawn from a deck. What comes next could be co-related to what was drawn first. When more of red or high or even cards were drawn first, the chances will be more for the black or low or odd cards to come out later, provided that they're drawn from the same deck. Sometimes in traditional blackjack, you have the possibility of counting down the favourable and unfavourable cards. Even if you didn't you're safe in assuming there's a slightly better chance of a win after a loss. Therefore generally a card game does not happen entirely based on a set of independent events, when the deck is not shuffled. This is why a deck is not used at one go till the end. Once it's shuffled there will be little or no relation to what happened in the previous shuffles. Therefore what you can predict from a count will be very limited. In online blackjack the deck is simulated to shuffle after each hand.
Sometimes, very rarely though, if you can predict the exact force and flying time involved, you might be able to know what's the outcome of a coin toss. Likewise, very rarely, certain level of predictability may be achieved for dice manipulation, wheel timing and shuffle tracking. Sometimes these could come in handy for games like blackjack, roulette and craps. It is also admitted that hackers are at an advantage to get hold of the random generator and decipher the next move.
There is no theory in online betting that if you keep on losing, you will never win, or vice versa. With your luck at the right time, you might be able to concert all your losses into great winnings in no time. This is the principle of online betting.