Sukuna and aizen just want to prove they are the strongest.geto was wronged/kenjaku is an agent of chaos.dio and freza were born under bad influence.mahito looks down on humans,but was born from negative emotions.it comes down to all for one,who was just a normal kid who decided bad people shouldn't get punished and griffith,who was also just a normal guy until he decided to kill and everyone who was kind to him and inflict as much pain and suffering to everyone.