Why are some people mean and aggressive?

Usually people are mean and aggressive if they are having emotional problems or frustrations in their life that's making them lash out. Counseling can help them!

It can also be due to mental disorders or psychological problems that go deeper than just emotions. They will need to see a professional psychologist or psychiatrist.

It can be a medical issue, like a brain injury or a side effect of medications or allergies, and it can be due to a hormonal imbalance as well. They need to have a medical checkup with their doctor.