Gambling is a game of probability, so many players are like you, they prefer to take half of the winning offer or amount, instead of losing it all and gaining nothing, while some other gamblers too are willing to give in all their hope on gambling continuously trying to double up their money and few times they could be lucky and most times they will lose all their money.
That is very true, some gamblers doesn't want a stop lost were they can take some part of the money, though disregarding some stop lost in gambling is understandable in some of the games that possessed playing probability, what I mean is that let's use Barcelona and Manchester United for example on this, let's say you play Barcelona to win and they have played 1:1 and even on this 1:1 Barcelona is giving so good that they are having several near shot to score on United and the time is still 65 minutes and the capital you use to stake has been divided into two, you wouldn't want to stop the lost because you still believe that Barcelona has time to give you the full money, perhaps that's how the mind of some works.