Throughout history there have been times when people had to pretend they were someone they weren't in order to stay alive. I would like to add to the 6th post. Some people lied about their nationality (if they were able to) in order to keep themselves and their families alive.
You could easily apply this situation to gays in the US military. While death isn't the consequence "coming out" for soldiers, it is the death of their careers, and automatically so accordingly to the law. So they must conceal their sexuality from everyone in order to continue serving. As of now, there are rumblings that this long standing policy may be about to change.
The question reminds me of Europe during World War II. Many courageous people appeared to be submissive to the Nazi regime, but they secretly were operating as members of the anti-Nazi underground. The activities of the French resistance have been especially well documented. Also, every European who hid or aided Jews in helping them escape the Nazis was living a phony existance. For all of these people, those of the resistance and those who defied the government to save Jews, staying alive themselves while doing what they believed they had to do required that they live lives of deception.
Phoniness and rationalization are different from one another. The former seems to indicate a level of controlling one's image to appear a certain way to another. There seems to be a deliberate justification behind this. It might be for survival or other interests. Certainly, the historical examples are quite relevant. In terms of daily lives, some individuals have to be "phony" in order to generate income or prosper. That is an individual choice. At the same time, human beings have to rationalize in order to survive. The level to which this is done might vary, but there are elements of the world or existence in which we block out to varying degrees in order to make life as something more livable.
My tenth-grade English teacher (some fifty years ago) told us once in class that if any of us knew the true nature of our existence, we would straight away kill ourselves. A bit shocking to hear such a thing at fifteen. And obviously the idea has stuck with me for lo these many years.
Do I believe it? I'm not saying yes and I'm not saying no, but it is a rather provocative thought. And so, to answer your question: perhaps we are all being phony in order to perpetuate our own survival and to make it through each and every day. I mean, what do we know? It's like that story about the fish:
There are these two young fish swimming along, and they happen to meet an older fish swimming the other way who nods at them and says, "Morning, boys. How's the water?" And the two young fish swim on for a bit, and then eventually one of them looks over at the other and goes "What the heck is water?"
I personally haven't been confronted with my own situation, but I can think of an example to give you: In the Mormon church, polygamy was practiced by almost all the members. Hatred and jealousy from non-members and apostates became so great that pressure was exerted against top church officials to abandon the practice and adopt the monogomous practices of the rest of the nation. To save the church from financial and economic ruin, Wilford Woodruff enacted a manifesto and the bulk of the members gave it up. Eventually, laws were enacted by the state of Utah making it a crime to engage in it, punishable by imprisonment. Many men and women went to prison for defying the law.
But, a few managed to go underground and secretly live it for many years. To avoid being arrested, they resorted to trickery, disguise, and telling "white" lies. Names were changed to protect the innocent. In many instances, the strategy worked.
Over the course of history there have been plenty of times and places where a person would have had to have been a "phony" in order to stay alive.
One example would be Spain in the time of the Inquistion. There were lots of Jews who had to convert (or pretend to convert) to Catholicism in order to stay alive. If they wanted to still practice Judaism, they had to be phonies.
A similar thing happened in Japan during the time that it was illegal to be Christian there. Christians were forced to desecrate sacred symbols as a way of showing they weren't really Christian. If you wanted to stay alive as a Christian in Japan during that time, you had to be a phony.
One last example could be the Soviet Union. At various times in USSR history, it could be fatal to disagree with the communist government. If you thought the system was bad, you had to be a phony to stay alive.
Historically, people have been phony to get through tough periods, usually that of discrimination, for example the Inquisition in Spain.