a cynic
Examples
A cynic is a man who, when he smells flowers, looks around for a coffin.
An idealist believes the short run doesn't count. A cynic believes the long run doesn't matter. A realist believes that what is done or left undone in the short run determines the long run.
A cynic is not merely one who reads bitter lessons from the past; he is one who is prematurely disappointed in the future.
Thrasyllus the Cynic begged a drachm of Antigonus. "That," said he, "is too little for a king to give." "Why, then," said the other, "give me a talent." "And that," said he, "is too much for a Cynic (or, for a dog) to receive."
A cynic by experience, a romantic by inclination and now a hero by necessity.
Idealist: a cynic in the making.