Stealing is a direct result of insecurity. If someone feels they don’t have enough (power, possessions, love) they will take what belongs to others in an attempt gain more ground. They will rarely steal only once because the drive stems from a deeper unmet need. Stealing, both overt and more subtle, can become a habit. Once a habit, it may no longer even feel like stealing; it takes on the form of entitlement. It may feel absolutely justified.
If others steal from us it can make us wildly angry; it can also teach us the importance of non-stealing: asteya in Sanskrit and one of the yogic ethical principles. It teaches us the dark energy that accompanies taking what is not ours, that in fact when we steal we affirm we do not have enough, that we are lacking and without. That when we steal we compromise our own integrity, and interrupt our sense of trust in others as well as ourselves.