Kevin McClory's Personal Vendetta Against EON
The whole situation with Kevin McClory is definitely one of the strangest and most convoluted in film history. As a writer myself, I'm a strong defender of writers getting credit for their work and protecting themselves from plagiarism. It was definitely wrong for Ian Fleming to publish the story idea that eventually became Thunderball without McClory's knowledge, and to use the story elements of Blofeld and SPECTRE. But I think we can all agree that McClory definitely got the justice he deserved.
He sued Fleming and successfully got credit, a settlement, and the rights to Thunderball. Fleming definitely paid for his misdeed. Then Harry Saltzman and Albert R. Broccoli treated McClory as fairly as possible, giving him a producer credit on the film version of Thunderball, and honoring their contract to only use Blofeld and SPECTRE for the next ten years (until Diamond Are Forever in 1971). So basically, McClory won! He got justice and was treated fairly.
So you have to wonder what was the point of even making Never Say Never Again? Even if it had been the most successful movie in history, he still wouldn't have been able to make a sequel or continue a rival film series (at least my understanding of the legalities was that he only owned the rights to the Thunderball story, and couldn't make any other James Bond movies). So what did he have to gain? It's like he just wanted to yell "Screw you!" at Fleming. I've heard that all three men (McClory, Broccoli, and Saltzman) had very difficult personalities, so I could easily imagine McClory not getting along with Broccoli and wanting to stick it to him as well. Pretty much the one success he had was casting Sean Connery, which gave him credibility. If he had had a new actor play James Bond, I don't think anyone would have taken the project seriously.
Personally, I actually enjoy Never Say Never Again and think Bond fans are overly harsh on it. It's a fitting finale for Connery in the role, has some good directing from Irvin Kershner, has a fun wink-at-the-camera sense of humor, and it's interesting to see alternate versions of the familiar characters. It's definitely just as good or even better than some of the other Bond films being made in the 1980's. I think it's perfectly fine when judged as a stand-alone movie. But when you look at its production backstory, you do have to wonder "Jeez, McClory, what the hell?"