How did Richard Pryor change his comedic style in the early 1970s?

In the early 1970s, Richard Pryor underwent a significant transformation, moving away from the clean-cut television persona he had maintained earlier in his career.1

He reinvented himself by developing a hard-edged, racially charged, and brilliantly improvisational style of stand-up comedy. This new approach drew heavily upon the characters he had encountered while growing up in the ghetto of Peoria, Illinois—including winos, pimps, junkies, and street preachers—as well as the increasingly baroque and personal details of his own troubled private life. His routines became known for their brutal emotional honesty, establishing him as one of the most influential and leading comics of the 1970s and 1980s.123