Firstly, the inflation doubling a few times before it flattens out means twice the supply, or from where we are, over 10x-50x the current supply (not exact but the point is there) means the price will go down.
Secondly, due to the way it is designed, if the 6 key trusted peoples did not "throw" their special keys away, they can create unlimited zcash and its impossible to know due to nothing being visible on the blockchain.
Thirdly, the anon feature by default is not on. Infact, I don't believe there are currently any transactions that allows the anon feature due to bugs. Furthermore, it requires lots of memory, 8mb of ram, to perform an anon feature.
Finally, there is the whole issue with "genius" tax giving early investors and and the team free money, which some people will try to fork or copy the coin.
Those are just some of the reasons, but the reason is primarily technical analysis for me.