Trauma is a killer of young people, and it's a global disease. If you look at why trauma patients die, the two leading causes of death depending on whether it's blunt or penetrating, are CNS injury and bleeding.
When I was starting my academic career as a trauma surgeon, you look at the landscape and saw, "Where can I make the greatest impact?" Dr. Trunkey described the trimodal distribution of trauma in the 1970s. There was early death within minutes, then there was a second peak within hours, then there was a third peak over the next few weeks. Over the last 30-40 years, the second peak and flattened out and the third peak has completely gone away. If you make it to the ICU, you will live. You make require dialysis, ECMO, etc., but you will live. Where patients continue to die is in the first hour or so after injury. If you have to look at this big number of patients and find where you can have the biggest impact, that would be hemorrhage control.