It's simple-- Ego, and ego fulfillment.
"I went to college and spent lots of money, so I could get a job that isn't one of those bottom-tier jobs! That's why I deserve more money than the bottom tier job holders!"
Basically.
The more specialized, the higher the pay, and the more distorted the view becomes. Say, Doctors-- After spending more than 8 years in college, they spend another 4 at least doing their residency where they get worked like F-ing dogs, on call 24/7, but they make freaking BANK after that, and can command lots of respect through their profession.
Similar with attorneys.
Both become HYPER specialized-- not just A doctor, or A lawyer-- they are an OBGYN, or an oncologist-- or they are an attorney specializing in patent law, or specializing in constitutional law-- whatever.
Somebody who can honestly do just about anything thrown at them, and do it well, but hasnt invested jillions of hours of their lives for a set of specific credentials will never get the pay that they are really worth. NEVER. (If for no other reason, the HR drones hiring them will feel threatened by the fact that the person who lacks credentials is getting paid more than they are, based on the actual merits of their work.)
Instead, society creates a total strawman out of these people, claiming that the blue collar workers are ignorant dumbasses that cant tie their own shoes--- Yet, put most of those specialists anywhere near the kind of versatility and variety in daily tasks that those blue collar workers daily handle, and most would explode under the pressure, or perform horribly in comparison.
Really, it all just boils down to feeling justification for having taken the expense to try and "Rise above that". When the "That" that they tried to rise above suddenly is coming up from below, it causes them to freak out. Instinctively, they try to shove the "that" back down again.
That's what you are seeing.