I really don't understand this line of argument and why you seem to be taking offense at an entire hobby. It's like asking why people who maintain home networking labs spend so much time and effort doing that when they could be putting those skills to better use at companies like Cisco. Or why people assemble computers at all when you can just get one from Best Buy. Why do people waste time with Raspberry Pi when you could do something cool with a real, existing exascale supercomputer?

There are many different niches in the amateur radio hobby. Some people want to buy off the shelf radios and antennas to make contacts over the air. Some people want to experiment with their homebrew designs and see how far their signal reaches. Some people want to experiment with very low power radios. Some people (including a Nobel prize winner!) want to experiment with new digital communication protocols for amateur radio use. And yes, some people want to use amateur radio for emergency communication purposes.

Why is it so wasteful for any of these groups to do what they're doing instead of applying their skills to something "useful"? Why is it any more wasteful than participants in other hobbies? That also ignores the fact that many amateur radio operators _do_ apply themselves to "useful" things: they're electrical engineers, physicists, software engineers, educators, military or emergency personnel, etc.