Many Indians who moved to the United States in the last few decades came here to study, and got into American universities by ranking at the top of their classes and already leading in their professional fields. Now, those Indians have made money in their careers and want to give back. Vinod and Gail Sahney of Concord were among 300 guests who attended the American India Foundation gala this month in Cambridge, where about $275,000 was raised to help rickshaw drivers buy their own vehicles. Vinod Sahney is a senior vice president at Blue Cross and Blue Shield of Massachusetts.