SAN FRANCISCO — Tom Steyer is a former hedge fund investor and a billionaire. Those things could be a liability for a man running for president as a progressive. But Mr. Steyer, who this month joined a field of — what is it now? — 24 people, argued this was a selling point.

“Now you know, I know everybody always describes me as being rich. That is not how I see myself,” he told an audience at a bookstore here Wednesday night. “But I can tell you this, the one thing it does give me is the right to say nobody owns me. I mean I will do exactly what I think is right.”

Fighting inequality is one of his priorities, he said, and his wealth is a sign of his ability to finance that fight. He plans to spend $100 million of it on the race.

A little more than a week after officially announcing that he is running to be the Democratic presidential nominee, Mr. Steyer chose a progressive bookstore and event space for his first campaign stop in his hometown.