The Internet is a huge self-controlled space with tons of information which is replenished every day and every minute. If many years ago it was almost impossible to detect who has plagiarized sentences from books, in our modern-day world a cheater can be identified in mere seconds. This is now possible due to the cutting-edge free online plagiarism checker for students and teachers.
The fact that all upper class people possess lots of money doesn’t necessarily means they are all alike. In the story we know that both Gatsby and Tom are wealthy, but they come from two very different backgrounds. Tom was born rich.