SpaceX spent $19.6 billion on spectrum everyone said was too small to matter. 65 MHz, a fraction of what any one of the big three carriers controls. Then Gwynne Shotwell explained where the cell towers go, and AT&T, Verizon, and T-Mobile fell 2 to 4% in an afternoon. The plan skips towers entirely. Starlink has 12 million customers with dishes bolted to their roofs, and Shotwell wants to attach a small cellular base station to the same mount. Every rooftop becomes a cell site. That breaks the…