There is no Nvidia — nor an AI boom as we know it — without Jensen Huang. He has reassured jittery markets with his words, bankrolled a trillion-dollar buildout and put economies on his shoulders.Now, the world is wondering if he can save himself.Why it matters: Global markets must confront a terrifying reality: The AI ecosystem's first "too big to fail" executive is suddenly vulnerable, and there is no backup plan if he is forced to step down.