Possible Reasons for Increase

Family units and social groupings have deteriorated, leaving accountability to others poorly valued.

Research shows that the students entering college now were the recipients of a lot of self-esteem curriculum in elementary education and as a result have an unrealistic assessment of their own importance relative to those around them. (Article)

Behavior that is rewarded is repeated, especially if it the payoff is like gambling. If they try cheating early in their school career, and get away with it at a greater rate than they get caught, the behavior will repeat.

Students are not emotionally attached to the institutions in which they complete their degrees. They don't identify with group organizations as much as students did in the past. By extension, they don't feel mutually obligated to the authority figures of an academic institution.

Litigiousness has created an environment in which the cost of pursuing discipline for cheating is much higher for the person seeking to rectify cheating, than it is for the cheater.