You're actually right because this option was careful brought by casinos to cleverly deceive people to lose more money because imagine some one who has about three game's left and has a high probability of winning but because of fear and knowing that they have an option to cash out and get small cash from the potential winning that they where to have and eventually cash out and lose out in the full money that where originally on the betting slip so this option is one that is beneficial to both the gambling company and the gambler
Yesterday I have made multiple bets and was sure that all of them would win. I have one one bet and noticed that second bet is about to get lost, so I have cashed out. Since I've been placing sports bets previously that day, cash out allowed me to return to an amount I have started. Spent time, ended with zero profit, but that to cash out I would have lost all the money. So much discussion here and still dont get why someone consider it as disadvantage or a trap.