Ramesh,
SAP SD is not about making a sale or about product life cycle.
It is about "keeping records" of activities related to sales and distribution -
the sale - creating sales orders, the delivery of goods to customers - creating deliveries, the bill to the customers - creating billing documents.
Above tasks are of users in a company that uses SAP.
For a consultant, you have to setup the processes so that users can do their daily jobs (above mentioned).
Market is tough for freshers.Getting a job is tough and may take months (even with certification).
From learning point of view, anybody can learn SAP SD.
TW