Kiddo,
I never said Chhetri is not a caste. Yes, it is a caste but the caste system rely on superiority/inferiority. Look at the figure below


I am not saying all Chhetris are "Chhetri" because they got moved down and once they were Brahmins. You didnt get my point. All I am saying is Brahmins were penalized for their  so called unethical behaviours by moving a step down. Lets assume a soocer game, if a player doesnot perform well on a game, the coach will put him on bench. But that doesnot mean all the players on the bench performed poor on the pitch and ended up on the bench. 

I dont want to talk about who wrote the caste system and all that sort of stuffs but we all interpreted the scriptures wrong. What it said was there are four castes and they were classified as:
 
SUDRAS- A person who is self centered, doesnot care about anything else but him/her self
VAISHYA- A person who thinks more than himself but limits to his family and goal of his/her life is material gain. (ppl doing business )
KSHATRIYA- A person whose goal is more than serving a family and serves his/her country (fighters, worriers,rulers)
BRAHMINS- A person who has a higher goal of living by studying and understanding the scriptures and spreading knowldege. His/Her purpose of life is to gain spiritiual growth and share it.
 
  Thats how it is mentioned and it says your life decides what caste you belong to. Since we believe in reincarnation, what we do today and how we choose to live will affect the caste we will be born in our next life.

p.s~ I have shared my knowldge and information. I am not advocating for a particular caste. I may not believe all the things I wrote since i presented it based on religious and historical information.