Pure horse feces. Williams rose to stardom on Happy Days, where he gave a killer audition for the alien part. The audition was totally unexpected and he was immediately hired and given a spin-off (Mork and Mindy).
Some people simply have talent. Williams was one of the greatest and gifted comedians of all time.
I think both statements can be true. He was undoubtedly a great talent but apparently was also a heavy cocaine user back in the eghties.