Why does biff steal?
Biff steals things because it is his passive-aggressive way of getting back at people he feels have unfairly done better in life than he has,
What compels him to steal?
stealing gives him an excuse to quit whatever dead-end job he happens to be in at the moment.
Future?
This pattern of subtle revenge and avoiding of mundane responsibility is exposed to be a nearly life-long pattern for Biff, and one that will continue.
