There are no demerits strictly speaking.Where are such questions asked,i wonder.Democracy is the finest system and most systematic and proper system.Though there can be some things said but only without any strong base which would make no sense.
The advantages of a non democracy are as follows.

In an IDEAL non-democracy,

1. Good decisions need not wait till the assent of all the institutions.

2. There is no wastage of funds or riots by public for/during elections.

3. The public are the main priority as most politicians in a democracy care only for power, money and fame. 

Pls mark as 5 stars if this helped!

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