A middle-class mentality is a toxic anti-intellectual mentality that takes people and societies backwards in life.
Signs that someone has this mentality are: Buying lots of things on credit and getting into a lot of debt, going to uni to get a job for comfort, living paycheck to paycheck, and not having a plan for the future.
People with this mentality also have a big disdain for rich and smart people as they see these pursuits as "egotistical". They think being humble is having no ambition and constantly searching for hedonistic pursuits. They're people who don't like facts and prefer to have an idealistic point of view no matter how destructive it is.
People who grow up with this mentality are typically middle class but it can affect anyone of any class. People with this mentality often leave their kids with very little due to the fact they don't understand money and don't have any knowledge to pass down.
"Simon says I think about money too much and I should just have fun because money doesn't last. But I want to make money because I grew up poor and I want my kids to have more."
"Don't listen to Simon, he grew up with a lawyer dad and doctor mom, money is nothing to him, he has a middle class mentality."