Good one, LOL!
It is for many popular philosophies, but of course one can also have positive philosophies as well.

No, philosophy is far broader in scope than a single negative emotion.

So I have to be depressed, AND I have to think? Sorry, I'll stick with the Vodka.

Philosophy literally means 'love of wisdom'. Socrates said:

"I am wiser than this man, for neither of us appears to know anything great and good; but he fancies he knows something, although he knows nothing; whereas I, as I do not know anything, so I do not fancy I do. In this trifling particular, then, I appear to be wiser than he, because I do not fancy I know what I do not know." Apology.

None of Plato's Socratic dialogues are positively resolved.

got even the remotest explanation why that could possibly be true? i don't buy it, myself.

g

I don't see the connection between Philosophy and unhappiness. You can be a happy or unhappy philosopher. Many times the philosophical perspective helps you deal with negative emotions by analyzing their source rationally. Of course it can eradicate happy emotions likewise, but if you are really serious about it this step doesn't have to make one unhappy. A buddhist-like detachment would be the more logical outcome.