Why was Daniel Ellsberg called the most dangerous man in America as noted in the nonfiction book, Most Dangerous?

Ellsberg had access to a 7,000-page top-secret report that told the truth about Vietnam. He gave a copy to the New York Times which began running daily articles on the report which became known as the Pentagon Papers. He was called the most dangerous man in America and a traitor by some – to others her was a hero and a patriot.