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.
It all depends on whether students gamble instead of entertainment, or instead of preparation time? Some may simply not play computer games, but prefer gambling instead, and then the time for preparing for exams will not change. And some may first play computer games, and then gamble. But in any case, I think that gambling is undesirable during studies.