Choose the word that can substitute the given group of words.

A person who is never happy with what he has

Malcontent

The word that can substitute the given group of words is malcontent.

• Malcontent means a person who is dissatisfied and complaining.
• Heresy means a belief or opinion that is at odds with established religious doctrine.
• Malleable means easily shaped or influenced.
• Miser means a person who is extremely stingy and unwilling to spend money.

Malcontent is the most appropriate word for the given group of words because it specifically refers to a person who is dissatisfied and complaining. It is derived from the Italian word malcontento, meaning "dissatisfied."