BHARTRIHARI, a 5th Century Sanskrit poet

The 4 categories of people. Valid even today.
  1. A good human being give up their interest for the well being of the others. They are the salt of the earth. Very few, very limited.
  2. Some people work for the benefit of others only when their interest is not hurt.
  3. Some demonic people kill the interest of others for their own selfishness.
  4. There is no word to define the people who kill the interest of others without any apparent reason. (Beyond demonic)

EKE SATPURUSHAH PARAARTHGHATKAH SWARTHA PARITYAJYA YE SAAMAANYAASTUPARAARTHMUDYAMAMRITAH SWARTHAVIRODHEN YE|
TE AMI MAANUSHRAAKSHASAAH PARHITAM SWARTHAAYA NIDHNANTI YE YE TUDHNANTI NIRARTHAKAM PARHITAM TE KE NA JANIMAHE||

BHARTRIHARI, was a 5th Century Sanskrit poet who used to travel, and study the world and the people. The 4th category of people truly exist and in large numbers.