It really depends on your circumstances.
If you just want to live with whatever you are doing now, there in no need
to go for further studies. You can always get promotion once in every 3-4
years if you work consistenly.
But MS/Phd is a must If you want to generate new ideas, model new systems,
understand research papers or publish papers if you think your BS knowledge is
not sufficient.
Doing MS is a long term investment. It wont just double your salary
or fetch you a promotion overnight. If you get into MS in IISC or one of the
top US univ, even if you have 10 years experience you can consider doing it.