In the documentary about Wim Hof (by Vice think), he was friends with a guy with terminal cancer who said doing the cold plunges made the cancer bearable and changed his life.
I mean he wasn’t claiming it cured him. He was just some philosophy professor who was suffering existential terror as one does at the end of life. And he said that doing cold plunges helped him, an avowed atheist, face death’s door with courage. I feel like that’s something that should at least give us pause, similar to how psilocybin seems to have a similar effect.