You're drawing the wrong conclusions from that quote. You can see your own faults in other people the way you're too blind to see them in yourself. What faults you see in others is within you, too. See someone being a slob, stealing, spewing hatred, being lustful, lying, etc? You have the potential to be that very same person and oftentimes we get annoyed the most when confronted with the very same defects we have ourselves. No, we should not sit back and enjoy the show if we care about what happens to our spiritual evolution. We should work extremely hard on improving ourselves each time we notice unethical feelings, thoughts, behaviors within us. If you could care less about what happens to you after death, by all means, sit back and do nothing.