It seems that we pay more attention or give more heed or are more influenced by miserable people than happy people?
For another words, one miserable person can outweigh the happiness of 1000 happy people?
Thus, do everything in your best power to escise miserable people from your sight, your environment, your home, your neighborhood, your social circle etc.
It is not your duty to “fix” or “help” miserable people. Also they are not bad people for being miserable; just treat them like they have the plague. They must be quarantined.