Dear Nikhil.
Firstly you decide--how many hours i can practice SAP in a day??
It depends on your commitment.(normally a fresher can practice upto 3-4 hours in a day by comprimising/leaving your luxurious life with 6.5pa salary--i am not degrading--it varies from person to person)
I strongly feel---dont leave your current job--learn SAP by spending 4 to 5 hours in a day as an additional activity..(this mistake i made--now i am suffering)
i know some FI Certified consultants --now working for 1.5 lakhs PA--ofcourse it depends on your knowledge.(they are good at their knowledge)
Dont be in dreams by looking into your sap friends and their perks--it takes years of time based on your commitment and luck(here your luck plays 50% role)
Also """""in my case Is it worth to invest in SAP & compromise on salary for two or three years?
Is it cost beneficial?"""
This kind of approach at entry level is not suggestible--here you are not investing in SAP (banking terminology--nothing wrong)--rather you are investing on yourself.
Phanikumar