The phrase "patience is a virtue" is just a way of expressing the importance of being patient. A virtue is a trait or quality deemed to be morally excellent and thus is valued as a foundation of principle and good moral being. Patience can make us better people. The definition of the word is to tolerate delay implying self control and forbearance. When we say "patience is a virtue" we are exposing our moral values and expressing the importance of patience as a foundation of principle. So to answer the question patience is not a virtue until it truly becomes a virtue and knowing how diverse the spectrum of individualism is I'm sure patience is a vice(opposite of virtue) to some. Patience is a necessity for a happy existence and that is why the phrase is so often used.
"Nothing gives one person so much advantage over another as to remain always cool and unruffled under all circumstances." Thomas Jefferson