Much of

software

are abstract concepts defined by the engineer.

Most 

emotions

referenced in colloquial terms -- like happiness, sadness are abstract concepts. There are underlying drivers to the eventual concept but the concept itself is still abstract by the time the human mind that is experiencing the underlying coins it as 'this is me being happy'

abstract concepts

can be useful for managing complexity and making information systems out of them as lego blocks.

They can be quite unuseful and cause much suffering when people enslave their sense of wellbeing to them.