I can call the API. Why does building the real system overwhelm me?

You called the API. It worked. That felt like proof you could build the thing. Then you sat down to build the actual system — the part with real users, real errors, real cost — and the ground disappeared. Suddenly you're thinking about memory, retries, evaluation, security, and cost all at once, and none of it moves. This is not a sign you lack the skill. It is a sign you are doing ten jobs in your head at the same time instead of one job with your hands. You have confused "the system" with "everything the system could ever need." No one builds that in one sitting. No one ever has. The fix is not to learn more before you start. You already know enough to start. The fix is to choose the smallest slice that runs end to end, build only that, and refuse to think about the rest until it earns your attention by actually failing.