There are plenty of people like him, but you need to evaluate pros and cons then decide
Ray is too big, min investment is 500k, but good people charge heavily their clients
Some of them like Seth Klarmann, they do not accept new clients
It is up to you to evaluate and decide.
It is not that I am skeptical about money manager, but I can handle better than them.
Sometimes people predict based on experience, and with some study or research materials. There are plenty of software available at high cost and people like Ray Dalio pay $250k to $500k level employ analysts to do their work.
We can also analyze/predict on our own, but it takes time, 1-2 years. If you review fundamentals, over all economy, at 100000 feet level you will be able to know market is exuberantly up or wild down. There are people like Robert Shiller who make wonderful studies, predict using their own measures (do not trust their TV/News interview). Their research are really good. It is again our focus that makes or breaks our life.