So much sympathy - I can really relate! I'm also pursuing a high pressure career; once in awhile I step back and realize that I actually have accomplished a lot, even if I don't feel like that's true. Sometimes it can help to talk with peers and get an "objective" view of things - we're often so poor at judging our own performance, and it's often unfair to compare our performance to that of others. We are different people, we take different paths, and we have different outcomes - and all of that is OK!

I go for months at a time, when depression strikes, unable to work on things about which I am truly impassioned. Similar thoughts, like "I can hardly learn this stuff myself; how could I teach it to others?" But like you, I can't see myself doing anything else with my life.

That's a gift! Not everyone is so fortunate to know their calling. Depression is even more painful when you don't know what you want to accomplish in life. To the extent that you can, keep that goal central, and remind yourself that others (with similar challenges) have made this journey as well - and you can too. This is what I keep telling myself lately. Other people with this same disorder succeed in this career, so I can do it too, even if it's really hard sometimes. The challenge is probably part of the appeal, but you probably can't really feel that connection right now. There's a big difference between intellectually knowing something to be true and feeling it, but keep reminding yourself on that intellectual level, and eventually it might sink down to the emotional level as well.

And maybe that's all garbage, but I think you shouldn't give up on your goals. We all have the potential to do something amazing, but it usually takes more than luck. Sticking it out through these tough times is part of the recipe for success.