What should I do to become a real fortune teller? Does society need such a career?

Divination does not seem to be a profession yet. In fact, divination is a potential psychological need of many people. If you really have this talent, then go!

Don't just rely on simple tools such as poker, it's just a game, not a real fortune teller. I suggest you read the Book of Changes, gossip and other books first, and then learn some Buddhist or philosophical theories. If you really achieve something, even if you don't go public, people will flock to you. It can also be a company, with the name of an advisory body.