You are welcome and thank YOU for stopping by :)
Boredom is supposedly the most common driver. Another one is the outward projection of problems. That means that people who are not happy with their performance, situation or life in general tend to find the reason for their own disappointment in others. That´s strongly related with envy, another cancerous characteristic.
I am not a psychologist but have been living close to people that faced these problems. It´s hard to wake them up.