Could this trait have also led them to some insanely extravagant public show of bringing stones all the way from Preseli? It would take a nutter to do something that barmy, I guess.
Yes, that's a good possibility - the bringing of the bluestones, the bringing of the sarsens, the crazy folly-like design of the monument - and of Silbury - all reflecting the insane ego of leaders. Think Saddam Hussein's huge statue of himself.... and then there's Ozymandias!