"Is the glass half empty or half full?” is a classic question, and a jocular message has been printed on many images:

Dear Optimist, Pessimist, and Realist,
While you were arguing about the glass of water, I DRANK IT.
Sincerely,
The Opportunist

The jocular “Opportunist” response was posted on Twitter on August 23, 2011.


Wikipedia: Is the glass half empty or half full?
“Is the glass half empty or half full?” is a common expression, a proverbial phrase, generally used rhetorically to indicate that a particular situation could be a cause for optimism (half full) or pessimism (half empty), or as a general litmus test to simply determine an individual’s worldview.[1] The purpose of the question is to demonstrate that the situation may be seen in different ways depending on one’s point of view and that there may be opportunity in the situation as well as trouble.

This idiom is used to explain how people perceive events and objects. Perception is unique to every individual and is simply one’s interpretation of reality. The phrase “Is the glass half empty or half full” can be understood also as a philosophical question.[2]

Twitter
Leighnda
‏@PeppermintPatee
RT @GreatScottinc: Dear Optimist, Pessimist& Realist,while you were arguing about the glass of water, I drank it! -Sincerely,The Opportunist
7:23 PM - 23 Aug 2011

Twitter
S. Wilson
‏@MeNTaLToXIciTY
“@GreatScottinc: Dear Optimist, Pessimist& Realist,while you were arguing about the glass of water, I drank it! -Sincerely,The Opportunist”
8:16 PM - 23 Aug 2011

Google Groups: DCW Behala
A good line for all
Sid
1/20/12
Dear Optimist, Pessimist and Realist,
While you were arguing about the glass of water, I drank it.
Sincerely,
The Opportunist

27 February 2012, Political Transcript Wire:
NATIONAL GOVERNORS ASSOCIATION HOLDS A PANEL DISCUSSION ON ECONOMIC DEVELOPMENT
FEBRUARY 24, 2012
(...)
AMY WILKINSON, PUBLIC POLICY SCHOLAR: Thank you for that introduction, and thank you to the governors for focusing on entrepreneurship and for the National Governors Association for putting it on the agenda so prominently.

I would like to start with a sentiment that is circulating among all of my entrepreneurial friends just this week. It goes like this, “Dear Optimists, Pessimists and Realists, while you were arguing about the glass of water, I drank it. Signed, the Opportunist.”

The Rambling Taoists
Monday, March 5, 2012
A Glass of Water
Trey Smith
(...)
COMMENTS
Joy 3/05/2012 02:41:00 PM
(...)
Of course, here is the best answer over all:
Dear Optimist and Pessimist;
While you were arguing about the glass of water, I drank it.
Sincerely,
Opportunist

Reddit—Motivation
Dear optimist & pessimist, While you were arguing about the glass of water, I drank it. The opportunist. Love, (pbs.twimg.com)
submitted December 7, 2016 by aamitgs