It's an adverse selection problem. There absolutely are predictive models in finance that work.

The people who make them will never publish about or describe them in detail, as they're too busy making billions of dollars on them.

https://en.wikipedia.org/wiki/Renaissance_Technologies

The people who publish their financial predictions or models are publishing them rather than betting money on them (or are trying to fulfill the prediction through the process of publishing), which tells you something about how confident they actually are in their predictions.