Visitor Visa - B2

Hi All,

I would like to narrate my experience yesterday at the Mumbai Consulate.
My background:- 26 years old. I am a Research and Development Engineer at a reputed product based MNC in Bangalore. I earn about 56k per month and have a decent bank balance(upward of 10L). I had mentioned in the DS-160 that I would intend to visit the US for my vacation. I was due to arrive on the 22nd of December ,2017 and leave the US on the 3rd of Jan,2018. I stay with my family(parents and sibling) in Bangalore and we have been here since 1990.

This is how my interview went:-
CO:- Good morning. Please pass me your passport.
Me:- Good morning sir. (Gave him the passport).

CO:- Why do you want to visit the US sir?
Me:- I want to visit the US for my vacation and spend my Christmas and New Years Eve there.

CO:- Are you working with XYZ company?
Me:- Yes. I am working with XYZ company.

CO:- How long have you been working with them?
Me:- I have been working with them for 4 years and 5 months now.

CO:- Where will you stay in the US?
Me:- I will be staying in San Jose.

CO:- With whom will you be staying there?
Me:- I will be staying with my friend < friend's name >

CO:- I am sorry sir but I wlll not be able to approve your visa. I am sorry. (Hands me the passport with 214b sheet).

My question is - I was not asked for any documents. I was carrying my employment letter, my payslips, my ITR, my bank statements, my leave certificate, my flight tickets(both to and fro), my friend's invite letter and her payslips. I have mentioned all the relevant information in the DS-160 as well. Why was my visa denied? I would also like to know the steps I need to take to get the B2 visa since unfortunately i have booked a non refundable flight ticket( I know I'm stupid) and I will lose all that money for no reason if I am not able to go.

What documentation can help me get the VISA? I honestly have a great job back here in Bangalore and have been here my whole life. I only intend to travel for the stipulated period.