As long as you don't play too long and you are winning and cashed it out, you are technically a winner.
However, if you play longer time and even while having lots of winning already, tendency is you are going to lose because of the house edge advantage.
it's really hard to quit when winning that is why there are more losers than winners. i have experienced it plenty of times, there is no winning in gambling except for the house.
Actually it is not that hard if you are able to manage your greed, you know that the house will always win but you are not even able to beat your own greed when you are winning. That's why you experienced it many times. Gambling should be considered as entertainment only if you are hard to accept losses. Means that you should spend less money than the amount that you can afford to lose. By this way, you wont feel sad too much as long as you can enjoy the game.