The role of possessiveness. The more possessive people are, the easier it is to get used to taking advantage. Because possessiveness can be obtained by constantly taking advantage of small things. Taking advantage of small things will nourish the growth of this possessiveness and become a vicious circle.
Lack of psychological satisfaction. By taking other people's things, or grabbing free and cheap things, you can get self-satisfaction to make up for the lack of emotion.