For a while he was.
Bill Burr nailed it on Arnold's career.
How many lifetimes would it take you to move to another country, then get famous for lifting weights while helping to popularize it as a sport, then become a movie star when you can't even speak the language well, then marry into that country's royalty, and then hold political office over the largest state in the country?
Arnold was in the zone for decades. If you watch Pumping Iron his personality just flies off the screen. He's more entertaining in that documentary than a lot of movie starts are in blockbusters.
I actually thing Arnold is an underrated actor, as crazy as that might sound. He's more of a movie star than an actor, and he's not a great actor in the traditional sense of the word, but he definitely studied the craft and is better at it than he had any right to be on paper.