I chew ice just about every single day and have never, ever had a brain freeze from it.

I have had plenty of brain freezes from slushes and shakes.

I so sometimes chew ice, I eat frozen mangos like popcorn, never a hint of brain freeze doing that.
I do get near instant brain freeze from eating slushies through a straw though.
The more you put it up against your palate, the more likely the brain freeze, so maybe how one chews ice makes a difference here.

I bite ice cream. I can have my teeth sunk in ice cream for literally a second.

I’ve never experienced the brain freeze, but sometimes when eating too much of something too cold I do feel pain in my gums/ inside my teeth. Most of the times chewing ice isn’t a problem for me.

Not that the brain freeze was due to drinking/eating something icy too fast?

When you chew ice, by the time you swallow it, it’s already melted in your throat.

Nah, it’s just hit or miss wether the freeze strikes or not. Can’t get closer to the thrill of real Russian roulette than this.

I was told brain freeze happens because of the temperature difference between the roof of your mouth and the stuff above it. If you start to notice brain freeze, it’s supposed to help to put your tongue against the roof of your mouth to balance the temperature back to normal.

This may all be bullshit. YMMV. This trick has worked for me.