At one point I had a bookshelf full of books on depression, fear, lack of confidence, etc., so it's impossible to answer such a broad question in a comment, but let me comment on the "high potential" sub-question.

Personally I no longer think that "high potential" is a real thing--I think of it more as of a mental trap that can play part in depression (it definitely played a big part in mine..).

What I mean by that (and it's not my own concept, I'm sure I read about it in one of the aforementioned books), is that the only reality that exists is the one we're living in right now. There are no other realities--unless you're dr Strange of course, I'm assuming you're not :)--where you're better off.

As a consequence, your place in this reality is exactly where you're supposed to be at this very moment.

Note that if you're in a bad situation, I'm not saying you should be happy about it, not at all!! I'm saying that given there's only this one reality that we have, if you are in a given situation then you are in the given situation and no amount of "what ifs" will change the present moment. It will only make you more depressed.

So this is basically acceptance. But the term "acceptance" can mean two different things to different people--I don't mean acceptance as in resignation or passivity ("it is like it is so it's all hopeless"), I mean something like "as of this moment the state of the world is XYZ and there are no other worlds in which I'm in a better place, so there's no point in beating myself that I could have done ABC. If I could have done it back then, I would have done it. If I didn't do it then that was the only possibility back then because as of now we're at the point XYZ, which is a result of me not doing ABC before (and of bazillion other events, so me doing ABC might still not end up the way I would think).").

Tongue in a cheek--I'm sure I could have written it more clearly :))

EDIT: I think I lost the "high potential" thread along the way. So: IMO "high potential" is a mental construct that can easily depress us. "I have/had such a high potential and I haven't used it. I'm a failure". No, stop!! This is a fantasy land!

You might have the highest IQ in the world (or the most flexible muscles, or whatever other advantage there can be). And you've definitely been using your IQ in your decision making, almost by definition. And you made the decisions you made yourself, correct? (I'm ignoring all the external interferences, as we're talking about "high potential".) Which means that you used your potential.

The fact that you can easily generate 100-digit prime numbers out of the top of your head doesn't mean that you can be top scientist just like that, because the scientist also need a reliable schedule, curiosity and tons of other things. And so the "high potential" fantasy is basically focusing on the prime numbers and skipping the other factors.

Now you can beat yourself that you lost you high potential because you didn't get up at 6 day by day to do some research. But that's exactly my point--you didn't because you didn't think it was advantageous to you, or maybe you did think that but you've had undiagnosed ADHD and that made it an order of magnitude harder.
So what I'm saying is that your actual potential has been exactly what you observed!

And if you're not convinced, or if you disagree with me, then I have one final question: let's say you really had a high potential and you really failed at it, and you're really a failure (all BS, but let's assume otherwise). Given that the past is gone and you cannot do anything about it, how does beating yourself help you?