The answer may vary from person to person based on the requirement, life style, aspirins and many other factors.
To begin with, a MBBS doctor can have a comfortable lifestyle without PG as many colleges in India require junior resident, demonstrators, Department worker etc. In fact, many other countries like Middle East and Commonwealth countries require MBBS doctors do perform various skilful performances. Financially also you become equipped where your package may range from 700$ to 2000$ per month depending upon the Hospital or College you work.
I do not encourage MBBS students not to do PG, because there is always a need and it is one of the mile stone in a medical student’s career.