a pessimist
Examples
A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty.
The man who is a pessimist before 48 knows too much; if he is an optimist after it he knows too little.
An optimist stays up until midnight to see the new year in. A pessimist stays up to make sure the old year leaves.
Scratch a pessimist and you find often a defender of privilege.
To an optimist every weed is a flower; to a pessimist every flower is a weed.
A pessimist is a well-informed optimist.