I was speaking of a world view not some momentary hope.
There is nothing wrong with being happy in an errant world view, like believing in Santa Claus or the tooth fairy, when one is 5 years old. It does help, I believe, in making the synaptic connections more varied than without such a wondrous fantasy. And for those with the intellectual capacity of a 5 year old such fantasies can help keep them controlled and productive.
But, as an adult, such fantasies, unless recognized as nothing more than feel-good fantasies, are dangerous. They, as we have seen so often in our history, lead to wrong ideas, wrong analyses, wrong decisions.
One might think they are happy in their false fantasy world but they cannot remain that way when reality slaps 'em in the head as it will do quite often. So much cognitive dissonance cannot make for a happy camper. Just take some of the folks around here. How happy can they really be when everyone is constantly telling them their favorite flood of 10K years ago didn't happen? Or that snakes never had a capacity to talk or that Earth really isn't the center of the universe.
Human societies have been steeped in fantasy world views for millennia and it has caused this species no end of disappointment, heartache and misery. Believing in some fantasy world view just because it makes one feel (momentarily) happy is to leave ones cognitive ability on the stoop while trying to engage the rest of the real world. Humans don't need any more excuses to be stupid. It's time to change that.