Why are people NICER to arrogant people??

I have noticed this many times. People trying to "Butter up" rude people and be nicer to them. For me,I did that back in college since I was uncomfortable to meet them everyday and thought trying to be nicer to them might make the scenario more lighter and I can go to college at peace.But now,I do not care.either I am never friends with them or I avoid/ignore.

Even now,I see lots of people trying to nicer only to rude,sarcastic people.I see them

complimenting them a lot and wonder why the heck they do it!!Now,we are more independent,not kids and we can manage our life without them.(I would rather be alone and do nothing than be with them).How come people r super nice to them?

Also,I saw in fb people liking every "nutty" snaps of those rude people.I personally know my friends who left college 12 yrs back and have absolutely no contacts with those bullies BUT only in fb.They like and appreciate every snap but talk to me as though they do not care about them.what's with that hypocrisy?why fuel the already arrogant mind of those rude people?

Why are people NICER to arrogant people??