Expecting big on gambling can indeed make us sometimes experience worse things, many people are addicted and experience life destruction because they expect too much on gambling while when they get results that tend to end in disappointment, they cannot accept it and have thoughts of wanting to recover losses that make them gamble again with the aim of pursuing victory which is actually something they should not do because defeat will be more dominant.
Exactly what you said gambling cannot be predicted accurately, some people believe that they can predict the gambling they do will be able to make them succeed in getting victory for sure but the results that occur are still defeats that occur more often.
A tendency to gamble more to recoup losses after a loss, this type of mentality is what causes gamblers to suffer the most. And it is because of this tendency that they fall into gambling addiction. They cannot get out of gambling even after facing many losses, they only want to compensate for their losses after losing, or when they win, they keep gambling to win even bigger. And in both cases, they can never enjoy the win, they only face losses.
However, there is a 90% chance of losing in gambling, so gambling should be seen only as entertainment, and maintaining self-control is very important.
Yes, this is one of the behaviors that can make them suffer because they will be trapped in a cycle of gambling addiction that does not allow them to be happy with their situation. Many people suffer when they are addicted to gambling and actually it is a consequence of their own actions which are not very disciplined in gambling. There is still a possibility that they can get out of their gambling addiction but this is very difficult because the process is not as easy as turning the palm of your hand.
The wrong mindset makes their feelings lead to things that should not be like the desire to get a bigger win that will be there and they will feel it when they have won, but with the risk of losing the same it is possible that it will make their feelings chaotic when the result is losing the victory that has been obtained.