Can anyone come up with a theory of how the 50% reward drop could lower the prices?
Yes, miners leaving when price has not rised, most investors having bought, "while still cheap" just waiting for price to rise, when it dont miners leave, causing lack of faith from investors and triggering panic, causing price to go even lower and even more miners to leave and Bitcoin goes really low.
I believe we might have to wait 4,5 five years for Bitcoin to stabilize.
There are 4 years ahead with 3500 new coins each day having to be bought to keep up.