Now it is official: living in denial is necessary. Especially in your relationships with others. Deny that your partner is cheating on you, you’ll be happier. Well, o.k., this is a bit of an oversimplification. However, the findings discussed in the linked article do suggest an explanation for why philosophers (and intellectuals in general) tend to be not as happy as they should be, at least if the Greeks were right.
If, as the article suggests, denial is real helpful in overlooking people’s flaws, especially if it is people we have a close relationship with, then it would seem that people will be happier in communities where such overlooking is more commonly practiced than in communities, where this is not the case. (There might be an upper limit of course. Maybe once you’re beyond a certain degree of oversight, things actually become less pleasant.) This allows them to be in denial over their own imperfections as well as those of others. It’s socially acceptable to look away.
It seems plausible (at least on the basis of anecdotal evidence) that communities in fact differ in the degree to which living in denial is socially acceptable. Furthermore, it seems very plausible to think that intellectuals in general have a tendency to form communities (both professional and personal) where looking away is socially less acceptable.
According to the above, then, it should be plausible to expect intellectuals to be less happy than the average person. Which again seems to be confirmed by at least anecdotal evidence.