I can identify with this, and (from previous submissions/comments) I get the impression that many others here can also identify (very high IQ, low satisfaction with life, anxiety, etc). FWIW, I have learned to "beat" the negative thought loops; after gaining some benefit from various efforts and experiences (which may or may not have been necessary steps in enabling what followed), what finally did it for me was understanding that the happiest people I know are also the most boring. Steady 9-5 jobs, steady relationships, relatively infrequent travel, often religious, etc. Those people didn't question a lot of the things around them, and they were generally happier for it. So I made a conscious effort to also become "boring" as much as I could, and (surprisingly) it more or less worked.

Obviously not everyone will be comfortable with that path (and obviously I still question some things, I just consciously choose to question much, much less than I used to) but I'm mentioning it as an option because it's basically the answer to that "pursuit of happiness" garbage that people always talk about. It's just a lot easier to be happy when you allow yourself to be pleased with simple things.