It's rare to find an ethical modern tarot reader who uses the tarot for prediction; like myself, nearly all readers prefer to use the tarot to empower their clients, by providing guidance in life's more challenging situations - knowing the likely outcome if nothing is changed, and learning what changes you can make (and how you can make those changes) to optimize the outcome for yourself, is clearly incredibly useful.

I have no idea which, if any, of the theories of why/how tarot works are correct - but I don't care; all that matters is that it works.