Why do parents choose words that cut,...?

like "I'm disappointed in you" and "you're stupid"--and "only a bull would be so stupid to even think that way." Some also called their child a demon. These words are merely because of the child's woes, fears, insecurities, questions, thoughts, and need for reurance. How can any parent think that these words will make anything go away...and not only that the child does not believe that they are okay and is piercingly wounded as well? This is not is not necessary a bad thing as a child who has strong enough mentality would probably be able to rise above it in time and perhaps attain much wisdom as well. But the issue is the child questioning whether their parents were necessary good parents and deserve praise, and wanting to believe that they were in fact good parents in some ways.