To be honest, I don't believe that patterns can be relied upon in pure luck based gambling games. However, I have a strategy that I used a few years ago that worked for me, but only when luck was on my side.
The strategy involves predicting whether a number from 1 to 100 is odd or even, and it can potentially double the amount you wager.
First, you would start by placing a bet of, for example, 0.001 BTC, and predict whether the number will be odd or even. If you win the bet, you will receive 0.002 BTC. If you lose, you should proceed to a second bet, but this time, with 0.002 BTC, and again predict whether the number will be odd or even. If you lose again, the next bet should be 0.004 BTC, and you should continue to double your wager until you win at least once.
Once you win, you should start from the beginning again.
It can work if you have a large enough amount to bet with, as the chances of losing 7 to 15 consecutive bets are relatively low.
However, I want to say that trying this strategy is at your own risk, and I no longer use it myself because I am not a fan of gambling in pure luck-based games. Personally, I prefer to gamble on sports games, as it adds an element of fun to the experience.
This is Martingale strategy you described. And indeed, it's impossible a pattern can be identified on this method. You can lose 7, 15 or even more times in a row, as results are completely random. You may think to lose more than 15 times in sequence is unlikely, but if you gamble consistently for several hours you will see it does happen more often than you expect.
It might be that Martingale gives us a false impression there is pattern which can be exploited through the strategy, but that is just our psychological working against us. Unfortunatelly most gamblers only see this once they lose their entire bankroll after a long loss streak.