Public opinion is of most value when the people who hold an that opinion.

The answer is voice. It expresses the sentiment that many people have an opinion about.  When someone voices an opinion shared by many, people rally around that and their opinions and thoughts are now heard by society which means it is something they feel strongly about.

glass wants to live in a world of super heroes and villains. he have lived all his life trying to be responsible for the creating the origin story of a super hero; he schemed and caused many incidents (many of them fatal) hoping that someday someone with superpowers would show up and save the day.

he knew himself very much. he saw himself as a villain of a real-life super hero story. he was aware of his strengths (more than smart enough for being manipulative and scheming) and weaknesses (having fragile bones and having to rely on his mind to succeed).