Most people want to see themselves as having overcome some sort of adversity to earn whatever they have in life, and that creates a bias to see one’s own life as unlucky and miserable. I definitely went through a phase of seeing my life this way as a kid.
This is your own bias speaking, you assume most people are just like you and that your own personal experience is universal.
Cognitive dissonance is the mental discomfort people experience when holding conflicting cognitions. It is a signal that our thinking doesn’t make sense and we need to change something to make that feeling go away. It is not hypocrisy or having contradictory thoughts. It’s a feeling we all experience. IMO exploring our cognitive dissonance is a useful way to better critical thinking. The people you are talking about are probably not experiencing cognitive dissonance as they have long since rationlised it away.