"It's better to be alone than to be in bad company" ~ Unknown 

When you're alone you can avoid getting yourself into trouble. For example you're in the library by yourself and your friends aren't with you but they are a bad influence. Versus you with your friends which are a bad influence and get you into trouble. What you should is is to be with by yourself and avoid the trouble around you. Being alone you can study for any test or what you don't understand in school. And being with your bad friends you would be taking a risk of doing drug of doing other unnecessary behavior.