I personally don't like losing, do you? But we all know that losing is part of the game and it challenges us to crave for the win. Who else dreamed of losing? Losing can be painful but some gamblers are immune to it and they don't lose hope until they got the victory. If I lose all my funds for a particular gambling let's just say I spend $5-$10 I call it a bad day and better luck next time.
No one per se enjoys losing but the reaction to the loss is what makes the difference and this reaction differs from person to person. Sound funny but true, some gamblers find a certain level of fun in the experience of losing in gambling. Some are also concerned with the social interaction among other gamblers and not the outcome of the game. Gamblers who are academically inclined can find pleasure in games like Poker and Blackjack and so the mental stimulation it provide is what matters to these people.
Let me point out that craving to win because we lost is not a good sign. A gambler can even record more losses if he is bent on recouping his losses. The inability to recoup the loss can lead to problems of anger, frustration, anxiety and even depression.