Ah, okay. I must admit that the depth of my knowledge on the economic history of my country is rather skin-deep. I do know, however, that we squander unbelievable amounts of money on war, so I think you may easily have a point.
How about WWII? At the end of WWII, the USA was certainly better off. The economic boom we experienced following the war was quite large, not to mention the baby boom.
Yes, and it would sustain less critical damage. I'm sure that both benefits contribute to the preservation of tail-rattling traits.
All of these sound like a posteriori justifications than a priori predictions. Good ones. But still.
I have observed that more ordinary snakes that have not developed a rattle often vibrate their tail in a similar manner, which often makes a warning buzz that is merely somewhat quieter than a rattlesnake's rattle. So incremental improvements to this rattling mechanism, which started with a regular tail, would just slowly increase the loudness, and thus warning ability, of a snake's tail.
Of course I agree with you. I am merely thinking in dollars and cents here, since that is the primary measure of value in the "civilized" world.