Trivializing is taking very real and major struggles that certain humans experience to much greater degree than others and pretending it has the same gravity as minor annoyances that a wide range of people experience.
If your comment is a joke or otherwise intended to be lighthearted, I apologize, but people saying in earnest what you said is a pretty major pet peeve of mine.
Real "Chronic depression doesn't exist because everyone feels sad sometimes" energy.
I agree that it's prejudice* against neurodivergence, but I just wanted to let you know that using the term 'retarded' as a synonym for 'bad or otherwise negative' is also prejudice against people with very real disabilities involving retardation.