In my opinion – and that’s all it is, my opinion – Jack held a love-hate relationship with the show.
On the one hand, he loved that Hawaii Five-0 gave him a starring role that allowed him to jump in with both feet and take off running. If McGarrett smelled a rat, as the old saw goes, he was out the door, down the steps of the palace, and squealing tires as he drove toward South King Street.
On the other hand, the business side of it all wore him down. It began with the death of Creator / Executive Producer Leonard Freeman midway through the sixth season. Being the uncredited Co-executive Producer and co-owner of the series, many of the duties once held by Mr. Freeman fell on Jack. During the ninth season, Jack asked to have others take on some of those duties.
By the end of the tenth season, other members of the cast were getting tired, as marked by Kam Fong Chun’s departure. The end of the eleventh season was supposed to have been the end of the series. James MacArthur went on to other projects. Jack is reported to have been seen walking and flexing his hands and arms in what was described as his shaking off McGarrett and reclaiming himself.
Except – CBS decided to have the show run for a twelfth season. Jack had to continue with a new team comprising William Smith as Detective James “Kimo” Carew, Sharon Farrell as Detective Lori Wilson, Moe Keale as Detective Truck Kealoha, and Herman Wedemeyer as Detective Edward D. “Duke” Lukela. It seemed to me that it took about four episodes for Jack to find his way back into the role of Steve McGarrett. Truly, he had made the break at the end of the eleventh season.
Some people claim the twelfth season was a miserable failure. I disagree. Some of my favorite episodes are in that season: “A Lion in the Streets,” “Good Help is Hard to Find,” “Voice of Terror,” “The Kahuna,” “School for Assassins,” “For Old Times Sake,” “The Flight of the Jewels,” “Clash of Shadows,” “A Bird in Hand,” and “Woe to Wo Fat.”
Too, the show wasn’t Jack’s only business venture. He also owned interest in a new shopping center in Hawaii Kai, among other interests. We saw it in “The Meighan Conspiracy” (Season 11). He had his philanthropic work for the State of Hawaii for helping to promote the Islands, Tripler Army Medical Center for supporting recovering servicemen, and Sertoma International for helping the hearing impaired – to name but three.
Yes, it was time for Jack to close his scripts, hang up his costumes, and retreat to his easel to paint yet another beautiful Hawaiian sunset.
I agree,H50. I once read,don't know where, that Jack took up acting because he hoped to become well-known so that his paintings sold more easily.