I wonder in every single day I met people, there should be at least a person who is disappointed on thing(s) happen to their life
These are few meaning of disappoint(-ed or -ment) I get from few sources:
- My electronic dictionary = fail to satisfy the hopes, expectations or wishes of.
- Wikipedia = the feeling of dissatisfaction that follows the failure of expectations to manifest
- Brainy quote = To defeat of expectation or hope; to hinder from the attainment of that which was expected, hoped, or desired; to balk; as, a man is disappointed of his hopes or expectations, or his hopes, desires, intentions, expectations, or plans are disappointed; a bad season disappoints the farmer of his crops; a defeat disappoints an enemy of his spoil.

They can say anything...