Your very question implies you don’t understand human behavior. Which is pretty normal … very few people do. But given that admission, I would ask you this:
If you don’t understand, then HOW can you be certain that what other people say is “not right”, or alternatively, that their “excuses” are not accurate/valid?
The short answer to your question is that ALL OF US have our thinking distorted & biased by emotional reasoning, motivated cognition, and homeostasis preservation. You are no more or less exempt than the people you criticize or judge!!
Dewey Gaedcke’s answer to Why are there so many bad mental health therapists?