Why do people do bad things like stealing,lying,murder& when it would be better to do the right thing?

Seems like people are the dumbest creatures on earth & yet the most intelligent what a paradox.Are we part demon & part devinne too?Most of us spend over 20 years just getting started in life,longer than any other animal. Are we the only animal that gets jealous,greedy, and selfish.Yet we have the holy scriptures that instructs us how to avoid these traits but few ever take heed. I wonder why would a person not want to be the best he or she could be.