I am not able to guarantee the accuracy at this point, but a specific book that I have read gives an explanation from God on this. It is a long explanation that is very deep - however, on the surface level of things, it explains that they had crystal based technology with some really big ones which they over amped and caused a cascade effect that destroyed them. In short, they suffered with a collective denial problem and lack of self acceptance emotionally. Due to this 'low self esteem' problem that was being covered over with bluff and arrogance, they sought to dominate the world and it didn't work out.
This is somewhat reflected by the remote viewing session from Farsight, although it's not 100% the same.