Winning is so rare to happen, you are right about that.
This is the big reason why we should be doing withdrawals whenever it happens not the other way around which is being greedy and trying to gain more.
It's better if take advantage of one win per day. If you happen to double your money, take it. It's not like we worked hard for it. A win will always be a win and withdrawing doesn't mean we are weak, in fact, it's the opposite of it.
Some people are so overconfident and that's why they find it difficult to withdraw their winning, they usually believe that they can use the initial winning to make more profit and on the process of doing so, they end up losing everything. Like you said, it's wise to withdraw some winning and only keep a small amount, such practice doesn't make us weak. Sometimes, I even withdraw my cash out offer while the game is still live.
Putting high trust in an activity that is probabilistic is the best idea to lead you to significant regret, I understand that the temptation of greed is something that is difficult to ignore, there are times for us to be careless and eventually fall, but of course I will not say that we should not put high trust in an activity that is probabilistic because after all luck will not always come according to what you want.
On the other hand, I believe that if a gambler understands correctly what is meant by "probability" then they should not feel confident that they will win again if they continue, because when you understand what is called probability then you will know that there is no connection between previous results and subsequent results.