Is it trendy? Yes.
Do they suck? Only at first.
Does it improve my life? 100% yes.
After 1+ years of committing daily I rarely get sick. And when I have gotten sick it’s been much shorter and less intense than what I have been used to.
Is this because of cold showers? Maybe.
Placebo effect? Also, maybe. There is more science coming out around this topic
But who cares? It’s part of my routine now and something I enjoy doing.