As demonstrated in The Great Gatsby, it is shown that illusions are made and kept by those who have money to gain power, for the purpose of manipulating those around them. When compared to the movie, People like Us, this occurs in reality as well. Some ways this happens is through special privileges, stance, and attitude.
For example, when Gatsby shows the card to the police when he gets pulled over, that is an example of how he has manipulated someone for power. By doing this he is saying, I know someone, so back off. This is also an example of how he would set an illusion. For the police, it is implied that if Gatsby gets a ticket, then some type of "punishment" would be brought upon them.
In People Like Us, this occurs too. For example, someone is teaching others how to act like they are upper class. For instance, not to turn their head past a certain point, and to stand within a certain distance from another. This shows that the "Upper class" has set standard, and if you break these rules, then obviously you must be of a lesser class. This is setting an illusion for those abiding by them as well. For if you don't follow these standards, then you are also doing wrong. By doing these things, you are lowering yourself in others eyes.
Fitzgerald has set the illusion the illusion that the upper class is above and beyond those who don't have as much money as them. Those in the lower class are in no way as good, and are being privileged by being in their presence. This thought of the mind is not too far off what people think. Those who are in special clubs, resembling the wasps or Jack and Jill, have been raised by these standards and will pass it on to others. The only way that illusions are set like this, is if someone lets them.