What three kinds of people don't laugh?

Generally speaking, it is generally believed that people should not laugh at the following three kinds of people:

People with physical or intellectual disabilities: They may feel inferior and vulnerable because of their own defects, and if they are laughed at, they may hurt their self-esteem and dignity.

People in distress or pain: These people may be experiencing something difficult or painful, and if they are laughed at, it may make their situation more difficult.

People who study or improve hard: These people may be studying or improving their skills hard, even if they may not reach the best level, they should not be laughed at.