Honestly, it rubs me a little bit the wrong way when people make fun of the idea of someone learning empathy at 35. It's NEVER too late to start doing better.
"It's never too late to change" is a good attitude to have in life, but it's not always borne out by the facts, especially on the subject of empathy and narcissism / sociopathy / antisocial personality disorder.
People like myself make fun of the specific idea that a sociopath can change ("Ian learned empathy at age 35").
Ian either always had empathy, or he will never have empathy.
Being unable to feel empathy is like being colorblind. You are never going to see certain colors, no matter how hard you try.
There is a percentage of the overall population, approx 1% to 6%, that have structural abnormalities in their brain that cause them to lack empathy in any serious sense.
And they will never have it.
A total lack of empathy doesn't improve with age, and it cannot be willed it into existence. The lack of empathy comes from deficits in the brain's frontal lobes and the limbic system, specifically reduced volume and grey matter in the ventromedial and dorsolateral prefrontal cortex, as well as impaired connectivity in the amygdala and reduced activity in the insula. (as well as the ACC). This is essentially damage, either genetic or acquired, that impairs normal operation.
People with these brain abnormalities are usually narcissists or sociopaths / psychopaths. They lie and manipulate. They have diminished or totally absent feelings of regret, remorse, or guilt. They do not experience the emotions that we take for granted that regulate our behavior. This makes their experience of the world totally different from the rest of us, because they are not emotionally bothered in the slightest when they do serious harm to others.
The reason people make fun of the claim that someone learned empathy at 35 is that you either have innate empathy "capability" or you don't.
You can't wish empathy into existence if you never had it to begin with
No sociopath leaving social destruction in their path is going to wake up one day at age 35, and start treating other people as human beings rather than objects to manipulate.
If sociopaths could be given empathy it would essentially be a breakthrough cure, but as far as modern medicine is concerned, we know the condition is for life.