I think the types most inclined to search for reason may be the most at risk, as there can be a fine line between an explanation and an excuse.
I've read that INTPs and INFJs are the most prone to suicidal ideation. This may result from a certain inevitability and tunnel vision that one develops in the search for truth. X is ultimately true, and I am certain about it; therefore... there is nothing I can do about it. Nothing I can do, nothing I can do. Nothing. Nothing. Brain snaps. Broken record.
Again, though, much of it is training.
Yes. This tends to be my line of thinking whenever I'm in a dark patch. When I feel that I have no internal locus of control, that's when happiness is a far away illusion that I can never attain. "Nothing I can do, nothing I can do" is exactly what the line of thinking is, yes. LOL.
Happiness, like all other state of being, is a momentary capture. We all live moments to moments. Our minds allows us the fortunate (and unfortunate) capacity to segue from one moment to another, to create this 'thread'...this holistic whole. Giving us an I. Me. You. Them.
Regardless of if we forget that the reality is that a moment can neither be created nor destroyed, only lived. Probability controls moments greater than any other thing.
Happiness is what it is, when felt. Nothing more, nothing less.
Yours (or my) considerations are moot. Talk of the human will, and it shall get you closer to the 'truth'.
INTP's seem to be the most miserable. We project the air of absolute logic, but deep down, we're all soft romantics, just below a layer of pscyhosis and rage that makes hittler look like a pacifist. Demons are this way too, but they lack the restraint.