Because that is what gambling is all about , trying to implant our mind about the winning probabilities but not the chances to win , making us believe that there are really ways to bet their site but eventually it will be taken away and they will be the one whos winning against us but we will keep trying our chances as we have already believe there is.
in gambling it is only the fun that we are surely to win and nothing more , if you win money then you are just lucky.
People do not like it when they do not win and they will always want to win therefore this make them to continue gambling until they have out of money to use in gambling. Some of them keep doing this until they get addicted to gambling, losing is painful and they do not want to feel that they have failed but when they get addicted, they would not know what they are doing. Gambling sites knows people will always want to beat their odd to win them therefore they set up their gambling sites in a way that people can not defeat it because if they keep defeating the system then it would not be challenging to them again. People love challenge that they will try to beat so they spend all their time trying to defeat that challenge and when they do, they feel accomplished.