Speaking from both personal experience and what I've observed from others- alongside the literature I've read for my degree- childhood trauma is pretty much a ticking time bomb.
You can examine the life outcomes of individuals who were traumatized and abused during their formative years then compare them against a "normal" population, and the difference is utterly staggering if you look at things like the ACE methodology. See this paper for figures on increased suicide rates in childhood abuse and neglect victims:
https://pubmed.ncbi.nlm.nih.gov/24629481/
I agree with the other posters that it isn't simply a matter of endocrinology. While hormones certainly do fluctuate during puberty and adolesence, one's exposure to different stimuli and experiences is what determines the trajectory of brain development for the most part, assuming we are ignoring complex factors like genetics.
In our minds, we have very intricate webs of neurons, many of them intertwining in ways that are not well understood yet. Over time, synaptic plasticity becomes more or less settled, as our existing neuronal connections strengthen due to repeated exposure to a stimuli. Or, these connections may weaken, if a stimuli becomes irrelevant and we never come across it again.
In early childhood and adolescence, these complicated networks are beginning to form and solidify, as our brains subconsciously catalogue each and every one of our lived experiences.
A tumultuous home environment, lack of attachment to caregivers and peers, bullying at school, poor health, abuse, traumatic events, etc can start priming your brain for a lifetime of misery/fight or flight programming.
For many of us, it's no wonder that we never recover. Adverse childhood events, in addition to sickness and intrinsically poor mental health, seem to have a snowball effect. When no one intervenes during these crucial developmental periods, you have to stumble through life with no guidance, attempting to navigate a world that has refused to offer you any sort of direction.
As a child, it is far too easy to slip through the cracks of the system. These broken children become adults who cannot function. The world is cruel and unkind to those who have suffered, and there is practically no support out there for people who have been deprived of proper nurture and support thus far. It only reinforces the pain we endured in childhood.
It makes me wonder if there is a point of no return for those in this position. I certainly think my ptsd will be a permanent fixture of my life for as long as I choose to endure this hellish existence. Of course, no one talks about this much, because it would soil the idea that every obstacle is surmountable and expose the gaping holes in the epistemology of our mental health industry.