What's going to happen if students go for exams with out studying & revising. They've got better chances to pass their exams if they're focused. Gambling's going to affect students focus it's a distraction which shouldn't be in their life.
If a student is distracted in class and neglects his responsibilities, he will not do well in exams even if he is not attracted to gambling. On the other hand, if someone is attracted to gambling but pays attention in class and uses their time properly, they will achieve good results even though they are attracted to gambling. Here, gambling will not destroy a student's career, but rather, if he is inattentive and does not use his time properly, he will destroy himself.
In fact, students can do many more activities while focusing on their studies and even be able to get attracted to gambling if they can control themselves. To focus on their studies, they have to be attentive in class but they should be more aware of their responsibilities. Yes, I believe that gambling alone will not ruin a student's career because they will not get enough money while they are still studying. Moreover, if they continue their activities secretly they will be responsible and will fail to pay the session fees and will be responsible to their parents and even to the educational institution.
Students who are inattentive to their studies can be inattentive in every field. Responsible students continue to make efforts and use strategies to have fun along with their studies.