I rode without a helmet as well for a while. My reason was because it was hard to find ones that fit my oddly shaped big ass head. I finally found one, Smith Variant, and I absolutely wish I had it from the start. I've had a mild concussion and a helmet would have prevented that. It was a minor crash, but as someone stated, the head hits the ground with the most force thanks to gravity.
Admittedly, it was uncomfortable at first since I was so used to just riding with a beanie. After two runs, I had already forgot that I even had one on. I actually went to scratch my head forgetting that I couldn't because of the helmet
But yea, I literally tried on 30 different helmets over the years. Smith Variant was pricey, but the adjustability and ventilation won my money.