I think the only way to rationalize a person becoming like Destiny is only through severe trauma.
Totally disagree. People become "like Destiny" through a complex interplay of genetic, environmental, and psychological factors.
Destiny exhibits characteristics of both narcissism and psychopathy / sociopathy.
About 1% of the population has narcissistic personality disorder (NPD), with characteristics like grandiosity, excessive need for admiration, reduced empathy, entitlement, arrogance, and exploitativeness, and vulnerability to criticism.
Somewhere between 0.5% and 4% of people are primary psychopaths / sociopaths (more or less the same thing, now called ASPD), with superficial charm, low impulse control, total lack of empathy, grandiosity, manipulativeness, irresponsibility, pathological lying, and lack of normal human emotions like guilt, regret, or remorse.
The internal state of a sociopath is totally alien to normal human experience as most of their external emotions are mimicry or merely performative, exhibited to manipulate the people around themselves in order to get what they want (sex, drugs, money, power, etc)
No one knows exactly what causes these conditions but there is evidence at least some part is heritable/ genetic. What we do know is that people with sociopathy have abnormal brain structures.
And of course, that these individuals leave a trail of social destruction in their wake.
Other factors besides genetics can include head trauma, or childhoods involving neglect and abuse, or even childhoods with excessive praise or criticism.
However, there are plenty of people who experience severe childhood trauma that do not turn into narcissists or sociopaths. So trauma alone is not a sufficient explanatory factor.
In any case, the presence of sociopathy or narcissism is multifactorial and is poorly understood, but there is no doubt in my mind that Destiny is a sociopath.
Whether Destiny was molested or experienced trauma is not really relevant to the moral and legal responsibility of his present day behavior, like pathological lying, manipulativeness, and blackmailing people with secret recordings.