I think they have held the cards since day one, and that is why nobody has tried to invade/ defeat them.
I saw a statistic. The latest Patriot system has a success rate of something like 175 intercepts out of 180 attempts, with ballistic missiles. So statistically, fire 180 and 5 get through. Ballistic missiles are easier to hit than drones, because ballistics have a predictable path. Drones change direction.
And once the Patriots are used up, especially when "wasted" against drones (small warheads) , the defender is near defenseless. They could fire WW2 era V2s, after that. Or in the case of Hezbollah against Isreal, their rockets made from water pipes and fueled by sugar.
I don't think it is the cost of the drone that matters. It's the value of the target. If the defender uses up their patriots and THADDS protecting hotels and the like, eventually the "essentials" such as airfields will be left wide open.
The PRC has had the same pre drone era missile doctrine for decades by the way, Fire thousands of missiles at a capital ship, and it just needs one hit. Hence the PLA rocket force. Now, as you say. drones have changed warfare, as Ukraine knows.
And these drones can be loaded into the back of a box van and fired from there. So is the plan to target every box van ?
It all adds up to.... Trump is an idiot.