Power
This career actually gives you quite a bit of power, or at least, influence, over the minds of your patients and their families. If you recommend to the court that Trinh should live with her grandparents instead of her abusive mom, your word carries real weight. If you convince the Johnsons that they must build their teamwork by teaching a squirrel to jet ski, they may well do it.
But please, don't do that.
The source of your power is the education and effort you've acquired from long years of training, and you must always take care to act in your patient's best interest, and not your own—even if it means returning the mini life vest you bought from Rodentwear.com.
As a researcher, you can potentially influence future laws or policies with your recommendations. Dr. Edward Zigler did just that as one of the brains behind Headstart, a nationwide program which provides early education, child care, and more to low income families. Even in your free time, folks will probably take you more seriously than Mrs. Leibovitz in 2A, just because your name has a Psy.D or a Ph.D. behind it.