https://pubmed.ncbi.nlm.nih.gov/17848828/ documents a single case.

https://pubmed.ncbi.nlm.nih.gov/31668156/ is a survey of 19 studies that identified 28 cases. Conclusion: "Of the 28 cases reported, 14 patients had certain precipitating factors like insomnia, lack of food intake, history of mental illness, stress, and psychoactive substance use."

Given the millions who meditate I think risk is less than a range of ordinary daily activities we engage in that can entail a life changing injury: crossing the street, diving into a pool to swim, and eating peanut butter (aflatoxin risk) to name three. The suggestion to consult a mental health professional, in the absence of any prior psychological issues that were significant, seems to me to be a waste of time and money.

Is there any way to know in advance if you are at risk? It seems to be beneficial for many as well right?

Based on the documented cases of psychotic break and the number of people who meditate, the odds are approximately a million to one in your favor of getting some benefit out of mediation vs. a psychotic break.

From what I've read, psychotic episodes were preceded by exceedingly long meditation sessions. Essentially, don't meditate for more than an hour a day and you should be okay, the psychotic breaks have a higher tendency to happen at meditation 'retreats' where they do like 8 hours a day of meditation.