No, and this is a conversation I have actually had with chronically happy people. Some studies have shown that mildly depressed people (not the sort of membership here) have a superior grasp of reality to joyful people.
The happy people I have discussed this subject with agree that it is a maladaptation which can compromise survivability, and this is why so many people like that wind up the victims of crimes and misdeeds at the hands of the unscrupulous. Some of them do succeed in life, while others wind up getting killed. The news is full of nice, friendly, kind, gentle and happy people who wind up entangled with seriously bad situations due to blind trust.
Cheerful Personality Disorder will never be formally codified as a mental illness in all likelihood, but the case is there that maybe it should be, since it can compromise survivability in situations where the extreme optimist does not recognize hazards in favor of automatically positive expectations.
Being a trusting person means that the trusting person is trustworthy, it doesn't mean that the trusting person can actually trust others.
When my response to Prozac was peaking, some of my chronically miserable family members who were desperate to keep me down became concerned that I was "flying high," but I concede there was indeed a point where my medication induced sense of optimism may well have been getting delusional. No, I may not have been at risk for committing suicide, but I may well have been at risk for getting killed due to obliviousness.
It's not normal to be happy all the time because that leads you down the road of ignorance and arrogance. People that think that the world is perfect live in a bubble and wear rose-colored glasses (is that how the analogy went?) They can't see or gain perspective beyond what's around their inner circle. I don't think they're genuinely happy, but more likely giving off a sense of denial and a bit of fakeness. Knew a lady that was happy all the time, full of life and love, didn't believe in depression and was ignorant of most of the suffering around. Really annoying and felt like she had a book of platitudes ready to hurl at anyone who was sad.
Generally, I believe what @KuriGohan&Kamehameha and @botanormal have already said, people hover in the middle, I try to be in the middle as much as I can. Too sad or too happy and I impulsively start destroying things or hurting others. Takes a lot of self-control to stay in the middle because humans in general are always about instant gratification or instant fixes to be happy. A lot of self-control and willpower to be humble.
https://en.wikipedia.org/wiki/Golden_mean_(philosophy)
