Grew up eating medium hamburgers and never got sick. Most did back then, it was common.
NO ONE believed in overcooking hamburger prior to 2010. Then the government decided “safety” required all hamburgers to be cooked to 160 degrees plus - a temp that destroys the bacteria within 10 seconds.
I ate thousands of hamburgers and never burnt them like that. My Dad would have died of shame. Never got sick eating a hamburger either. From bad seafood in restaurants? Yes. Hamburgers? Never.
Best temp IMHO for a burger is no more than 125. 160 is charcoal.