The word we should keep trying really sounds to me like encouraging to gamble for more then experience possible addiction in long run. I don't want to test out myself towards this and chase something since I know how casino works.
That's the reason I just don't give any damn towards those people saying that they have working strategy since after all every result is actually unpredictable. We might win on some of our prediction but for sure its not going to last long. That's why I'd manage to have limited budget and session so that I don't exceed on my limits then could recover easily if I experience bad luck.
Perhaps what is meant by "we must keep trying" is not to mean that we must continue gambling in a short period of time or to chase losses, but rather within a time frame that you have agreed upon (consistent and scheduled). For example, if you bet/gamble once or twice a week, you should always try at that time in the same context or game. Of course, this is not a reliable strategy, meaning it is impossible to always guarantee winning, but I am sure that as disciplined gamblers, they will schedule their playing time.