> Most of it is pure fantasy including the idea that 3D printed missiles are going to start striking US strike aircraft at 40k feet

Nobody is really talking about hitting supersonic jets at 40k feet, nor even destroying a fully-armoured tank. More about making your opponent think twice about deploying close air support, and have move cautiously with their APCs and supply trucks.

We can see some version of this playing out in Ukraine, and I guess it is possible that FPV drones have pretty much invalidated the role a DIY missile launcher would play