I haven't been diagnosed with anything "yet", I have trust issues with mental health professionals, I'm a high-functioning person. I perform above average under pressure (when starting a job for example) and once I get recognition from my boss and coworkers I lose all my motivation, like all my intellectual energy was focused on "impressing" others, I don't see any more challenge, I start finding all the flaws and imperfections in the systems and processes, I get annoyed by all the inefficiencies, I get bored (the "what am I doing wasting my time here" syndrome), then depressed, then I quit or change jobs. The good part is I've gotten raises faster than my peers from job hoping, demand is high in my field so I've never been out of work since 2005, having experience in different companies gives you a better over view of the industry, rubbing shoulders with people from different companies is good for networking, it's not all bad except I haven't found something that keeps my motivation going. One ingredient that's missing in my career is creativity, which I have tons to offer, but I'm locked in a high paying non-creative environment, while all the artist and creative people I know are broke. I feel like I'm selling my soul to the devil and that doesn't help my depression issues.
This is not a recommended solution, but an observation of my own life. I felt almost exactly how you did - till I had kids. They gave the job I was once excited about, now bored about, a new rich level of meaning -- bc it was allowing me to provide a better life for them. They gave me a reason to have long term goals there, and not throw in the towel as quickly as I might have otherwise.
I might feel the same way if I had kids, but I'm scared to death of having children before finding my true vocation. I think if I have kids and find myself "forced" to stay at a high-paying job I didn't like, I would be an unhappy slave. Perhaps the love for my kids would totally make-up for that, but that's how I think now that I don't have kids. I'm an idealist and I want to be in love at home as well as in love with what I do for living. I know I set the bar high. Right now I'm studying a lot about the Myer-Briggs personality types and I'm finding a lot of answers. Thanks for sharing your observation.