The incentive to work in the job often carries over into other areas, such as school. A teenager might decide that he does not like his minimum-wage job, and therefore will work harder and continue further in school, in an effort to secure a better job for the future. Without this valuable experience, the incentive to work hard in any area will be reduced. A job also occupies much of the youth's time. An increase in teenage unemployment means that time will be spent in an unproductive and possibly dangerous manner.
Idle hands are the devil's workshop.
Free time can lead to excessive drugs, alcohol, crime, sex, disease, and other such harmful activities. Then there are working conditions. Those who do hold on to their minimum-wage jobs might not be treated as well because they can be more easily replaced. They might not get the hours or vacations they request, because the employer will likely not be as cooperative. With thousands of other people available for hire, the firm is less likely to meet anyone's needs.