The problem with anxiety and experiencing this inversion thinking is that it is a constant bombardment of everything that can go wrong. Combined with PTSD/CPTSD, the brain is in constant “danger mode”, looks for all kinds of dangers, not just the ones we have control over. It is a terrifying way to go through life. I’ve been in therapy for years and yes, countering with what can go right is one of the coping techniques, but it takes extreme effort. Constant effort over years and years to change these thinking patterns, to lessen the anxiety of what can go wrong to the point that it is actually useful again. Until then, the brain rapidly rejects thoughts of what can go right, because it is so strongly convinced that things will go wrong.
The goal is what you are saying, yes. But for a lot of us it takes completely rewiring our brains to escape the constant bombardment of thoughts of danger, to avoid the fear and anxiety. It isnt as easy as just flipping it around.
This is similar to the advice people give to depressed people about looking for positives in life, sure thats true and will help eventually, but there is so much more work that needs to be done when the brain is in a really bad place. It doesnt really help to say “just think of the bright side!”