Minato is glad that he has helped all those people he'd met in the past year.
He didn't complete their social links for power; that would be wrong, but in some cases, he thinks that to himself. Maybe, each one of those people have something that they'd like to believe that for reasons he had helped them. Put it simply, he helped because he was there, because he could.
He knows the truth.
Because, he knows that after he maxes them, they won't need him anymore. It means that they are willing to look toward the future, ready to grasp life with their own hands. It means that they will selflessly charge forward, ready to plan their lives, knowing full well for what they'll live for. It means that they take life into their own hands, and live according to their own wills.
It means that he's done what he's wanted to do.
It means they'll be ready for whatever their lives have to offer.
That means when his time comes, hopefully, they won't stop to mourn.
Because, he'll be protecting them, so they can live their lives to the fullest.