Here is the deal...
When was the last time you, and I say 'you' generically not personally, re-purpose an AK-47 into something else? Or how about a tank? Or a jet fighter? Or a missile?
Tools of war are designed to be destroyed. Weapons destroys things and kills, yes, but in the risks of war, we also designed weapons to be losses, never for profit. What it mean is that the moment you bought a rifle or even just one bullet, you have essentially used that rifle and fired that bullet.
A $1 million missile to destroy a $30,000 truck is a good deal. The missile was designed to be a one-way weapon never to be recovered. The truck cost less to manufactured but has much greater value, or return-on-investment (ROI), because the truck can be used to transport anything from soldiers to supplies. The truck can be re-used many times. The missile can be used once and because of that, the missile must be overbuilt so that its components do not degrade over time from day of manufacture to day of use. Not only that, the missile can be designed to be used against different targets under different environment, so this requirement will drive up cost.
Same idea applies to the airplane. The value of a UAV is not how much it cost to manufacture it but what can it do over enemy territory, so destroying it with a more expensive manned 'top-of-the-line' fighter is appropriate. We just deny the enemy something much more valuable -- information about ourselves. The SR-71 cost much to manufacture and maintained over the decades, but the cost to our enemies were inestimable based on what the airplane did.
Let me put the issue on a more personal level...
If Mike Tyson gave you a concussion, broken nose, jaw, and several ribs. Are you going to laugh at him because he spent millions in training over the decades just to beat you up in a few seconds?