Glory
People are separated from their family members and loved ones every day. Oftentimes, private investigators are hired to find the birth parents of an adopted child. They also help parents find children they didn't want to give away. You experience the glory of reuniting people with their loved ones. Tears of joy are your reward—those and your paycheck.
To a PD, public and federal records can also be sources of valuable information as long as the person knows the legal name of the lost individual. Sadly, you won't run out of missing person cases anytime soon.
With over 400,000 missing kids in the U.S., police departments become overwhelmed with cases. That's when they call in the PDs. Private detectives are often hired to find missing children, and there are thousands of success stories.
You can't tell us rescuing children isn't glorious—that's almost the definition of being a hero.