What if one or more of these necessary items is not available no matter how hard a person tries? A few examples: no arguments about how important it is to follow a balanced diet, but suppose a person is homeless and hungry. Any kind of a diet is better than none. Or sleep: absolutely, good sleep is crucial, but what about a person whose trauma manifests as chronic insomnia, and who has sought treatment for it to no avail? Or the first item on the list: what if a person has sincerely sought such treatment and it is not available? Trauma therapy is not widely available and often expensive. Some people don't have that option much as they want it.
There are still choices to be made... and I also concur with your refinement, that the outcome is not necessarily entirely your choice, but your choice/s has a part in your outcome. Trial and error, that is healing trauma and learning how to manage your PTSD specific to you.
You have to apply common sense at all times. You talk about diet in combination with being homeless. Which is more important from a common sense view, focusing on not being homeless and stabilising your lifestyle, or what you eat? Common sense says the former. The latter comes later, once the former is achieved and a balance is present.
Sleep. You cannot treat symptoms, you can only mask symptoms. Choice comes back to trying to treat a symptom versus trying to tackle the core issue.
That goes hand in hand with your last example... $$$ for therapy. Ok... for those who think the end game is all about having a therapist, you're wrong. A therapist is a guide, they're a source of information and experience. You have to pick and choose what works for you and what you apply to yourself. Having a therapist is great, no doubt about it, but you can also achieve the exact same outcome through this forum and via books and self-help. It is factually proven that bibliotherapy is just as effect as face to face therapy. Look up studies... especially in depression and anxiety, bibliotherapy (self-help books doing it yourself) compared against treatment with a therapist, typically obtained equal results, and you will find those who completed bibliotherapy methods actually have better longevity results, as they had to educate themselves plus do the work. So there is a choice when you don't have all the money for expensive therapy.
Choices exist. Like what has been said... you can wallow around and make excuses as to why you can't do something, or you can make a choice and find an alternative that will work as effectively.
When in doubt, just ask, is my motto. I've leaned on good friends who are shrinks for a decade now... honest ones without all the psychobabble bullshit, and the results for a person can be obtained many ways. Don't get me wrong though... a therapist loop is an excellent loop to have... but it comes at a high cost. You can use forums like this to substitute that loop, because the sheer opinions and ideas you get back give you choices to use.
There are problems, and there are solutions and alternatives to those problems.
I've had people tell me they don't have $20 to buy a book to help themselves, yet they would then buy marijuana, cigarettes and alcohol to help them cope. That is an example of the realistic shitty choices some people make. You either want to get better, or you want to make excuses. It is that simple and there is no immediate time frame. One issue at a time is how you do this.
When I started this forum, I used to use the term, baby steps. That still applies today, I just don't say it often.