There's been questions about him before. You can check some of these while you wait for a ne new answer:

https://www.reddit.com/r/AskHistorians/comments/dduble/can_someone_give_a_concise_summary_of_what_a/

https://www.reddit.com/r/AskHistorians/comments/3uw2ra/how_do_historians_feel_about_graham_hancock_i/