Nobody disagrees. But a high level of disparity historically has let to collapse and the current level is the highest in recorded history, even compared to the extreme level just prior to the Great Depression. See my other reply to you.
The mere existence of the level prior to the Great Depression did not trigger the Great Depression. Again, you're trying to use macro-aggregation to reverse engineer a point that does not exist.
The Great Depression was caused by government manipulation of the money supply, and was exacerbated by FDR's further intervention in the early 1930's.