Manual transmissions are not "an order of magnitude less complex and cheaper." They're far more expensive because the volume is much lower and every configuration has to be crash-tested, so the cost of that crash testing is amortized over a much, much smaller number of vehicles.
Manual transmission vehicles get significantly worse mileage and this drags down the fleet emissions which means they need to spend significantly more pushing out low or zero emission vehicles, or can't produce as many SUVs and trucks, where the profit margins are highest.
Porsche and Ferrari don't represent the market as a whole, or any significant portion of it. Both are acquired to a large degree as investments - they often appreciate in value if well-cared for, or at least lose significantly less value compared to the average vehicle.
People are buying manual transmission vehicles because they're rare and likely to appreciate in value more, not because they're better in any sense. They get worse gas mileage, are slower, and less capable. Dual-clutch gearboxes can shift fast enough that the limitation in them is the rotational inertia of the engine, to the point that there's little or no interruption in delivered torque, thus enabling shifts without upsetting the balance of the car. No manual transmission car can be up/down shifted during track in / cornering / trackout without upsetting the car's balance; dual-clutch gearbox cars can be. And lastly, they can have more gears.
Early gearboxes had longevity issues (clutches) but that's largely been sorted out and is no worse than manual transmission cars.