Why does she steal?

In small measure, to feed the disease.
In larger measure, because she feels entitled.

Because she resents any situation in which someone else has something that she doesn't have.
Because she wants to inflict damage, and theft is low-hanging fruit.
Because she wants to deny others the comfort of contact with objects from their lives which have become invested with emotion.
Because she wants to make others feel the pain of loss.
Because she imagines she can get away with it.