determinism as an idea can be harmful to the human psyche. It's easy to fall into a nihilistic trap of "my actions are not my own, and nothing i do matters". People with that mindset turn to hedonism or nihilism. If they truly accept those words there would be no escape through existentialism or absurdism, they'd just be trapped.

i imagine only a tiny number of people would find the ideas determinism presents comforting, as they can feel free of consequences that are truly their fault (which is also a bad thing)

we have no way of telling which one is true in the determinism/free will debate, but if we live believing we have no real choice or say in what we do - it's going to be universally worse for everybody, as people explain away ever bad action with "i guess it was always meant to be"