With over 4,000 posts in this thread, I doubt I can bring anything new to the discussion, but I'm going to try anyway.
A couple days ago, I took a spill. It was almost a non-event; I ended up with a skinned knee and elbow, and a sore hip. I also noticed a stiff neck that became apparent long after I returned home. It felt like whiplash, and I didn't think much about it at the time.
That was Monday. I didn't ride yesterday, but decided to go for an easy workout this morning. When I started to put the helmet on, I saw a big scuff on the side. I then saw a crack. Apparently my head hit the pavement hard enough to ruin the helmet, and I didn't even notice at the time.
I'm wondering what might have happened without the helmet.
Anyone who chooses not to wear a helmet knows better than I what the value of their head is.