Shouldn’t cause hair loss at all. Think, if you cut your scalp doing stuff, does that cause hair loss; no. Stress can trigger hair loss so anxiety over getting the biopsy could mildly contribute to hair loss. I’ve battled with the road, dirt, rocks, and cars on a bicycle and been involved in insane crashes where I lost a lot of skin including my face and head. I always wear a helmet, but have had damage from glass inside and all around and can say that never caused hair loss.

Pain is relative and different for everyone. I have never had a biopsy, but I can say that nothing that is done in a hospital or medical environment is a really big deal, at least anything I have experienced. However I break bones like ribs in a crash and still ride my bike home for a dozen miles like a badge of honor.

So you have incentivised crime against society for survival.