I would hate to meet Seligman's optimist. And so would you.
The optimist is:
Actually, Seligman does meet ideal optimists a few times in the book. He hates them. One of them is a woman who bawls him out for everything, including a broken hairdryer. The other is a man on a plane who immediately starts bloviating about his job, how great he is at it, and so on. Seligman's reaction? "Oh no, a talker."
The most optimistic people he tests are... insurance salesmen. No further comment.
The optimist is Donald Trump. It's a salesman. It's a self-obsessed youtuber. It's a climate change denier. It's Brent in The Good Place. It's presumably Seligman himself, who spends a very, very large portion of the book talking about himself, how smart and scientific he is, what prestigious people and institutions he spoke to, how much money he made by selling companies optimism tests, how good a guy he is, how all the behaviourists are stupid chumps compared to his amazing insights, and so on - while promising you he'll totally teach you his techniques at the end of the book after all this guff. Optimists are people you (if you're like most people) would personally avoid. (Yet somehow the public inexplicably want to vote for, watch and funnel money towards.)
Seligman does ask himself why pessimism still exists, even though the optimists are happier, more successful, richer, and just better adapted for a modern world in which nothing much really goes wrong any more. His answer is that the pessimist is more accurate, sees the world in a more truthful way, and sometimes that's needed. The evolutionary world was harsher, and the pessimists were the hard-working ants to the optimistic grasshoppers.
I think another answer is that optimists are fucking annoying and people dislike them. Pessimists come across as humble, truthful and friendly. When an optimistic sportsman fails to catch a ball, Seligman says, he gives the reason as something stupid like "the ball was slippery." The pessimist gives a funny, truthful answer - "It was very catchable, but I didn't catch it". Which guy would you actually want to hang out with, joke with, marry, have kids with? The moronic optimist who keeps telling you not to worry and blaming you for their failures while taking all the credit for their successes, or the pessimist who shrugs and admits they screwed up?
I also cannot square Seligman's main hypothesis - that learned helplessness is a factor in depression - and his description of the happy, successful optimist. The major factor in whether you develop learned helplessness or not is control. But the optimist, when he experiences something bad, attributes it to something out of his control. Nothing he can do - the ball was slippery, the car broke down, the other guy was a better speaker, I'm just not a morning person. Why is the pessimist, who attributes both good and bad things to their own actions, not less susceptible to learned helplessness?
This book gives a horribly accurate insight into the optimist-run world we live in. They're wrong about everything and happy because of it. They don't want to hear your boring pessimistic facts about world politics or climate change or whatever. They just want to make their ten insurance calls a day.
If you're depressed read Feeling Good instead. It's less... depressing.