I completely agree that there are tragic cases where trauma has such a profound impact that recovery is limited or even impossible. What happened to your DM is horrific and utterly heartbreaking, and I wouldn't suggest for a second that someone in her position can simply choose a different mindset.
I think we're talking about two slightly different things, though. Your DM sounds like an extreme example of trauma causing severe, lifelong psychiatric illness. In those circumstances, the trauma and its consequences may indeed dominate a person's life.
My point was more about the general discussion around trauma and identity. For many people, trauma explains some of their behaviours and struggles, but it doesn't mean they are nothing more than their trauma or that healing and growth are impossible.
Acknowledging the impact of trauma and encouraging people not to define themselves entirely by it aren't mutually exclusive ideas.
Even in very severe cases, I think there is value in trying to find the person underneath. In fact, I think defining someone solely by their trauma can be quite depersonalising. Trauma may have profoundly shaped their life, their behaviour and their mental health, but they are still more than the worst things that happened to them.
For example- a woman with severe childhood trauma may be hypervigilant, anxious and distrustful. Those are trauma responses. But she may also be funny, creative, intelligent, compassionate, stubborn, curious, or have a love of animals and her children. If we focus only on the trauma, we risk missing the whole person and to me, thats literally robbing that person of their own sense of self.
To me, there is an important distinction between saying "this person's trauma has had a devastating impact on their life" and saying "this person is their trauma."