It's frowned upon to be self centered.
Bob takes Jamal's bike because Bob wants a bike for himself.
Jamal wants to teach Bob a lesson.
Jamal points out to Bob that if he cares for others, others will care for him too.
Jamal takes everything he can from Bob because Jamal wants things for Jamal.
Bob decides to give Jamal's bike back and care about people besides just Bob.
Bob learns that whoever steals the most stuff has the most stuff.