There should be a definite difference in severity to those with open bullet/shrapnel wounds entering the skull or cracking your head open on cement steps like you did compared to having your bell rung as you describe getting the head jerked back and forth. Maybe they have differing trauma levels but call it all the same (TBI) and the numbers like 300,000 would be more understandable. Just the numbers seem skewed, in the ten year Vietnam war there were 303,000 wounded from all sources.
It’s because Medevac and life-saving procedures have dramatically improved since VietNam.
Soldiers today are surviving wounds that 50 years ago would most certainly have been fatal.