Now, note that what I am stating is merely observation of @ninjahaku21art publicly shown development of Vincent's character from a Psychology student and a weird ass nerd.
Historical context is what sets and bakes this cake perfectly. Following the fact that the time era stayed in the Cuphead 1920~ era, we know when this would all be in the development and processing of understanding mental health. But at this time the fundamentals of psychological knowledge inst even there. They were just starting.
Because this means mental disorders or unusual behavior wouldn't be seen or addressed as an issue that would need to be in today's circumstances. While Ninja had stated shes unsure of Vincent being an actual sociopath, he still expresses a hell of a lot of sociopathic tendencies that i will be referring to as he still expresses them as habits.
I AM NOT DIAGNOSING HIM AS A SOCIOPATH
Let's start with his behavior as a child. The animal killing, the harassment against his cousin and house staff, other than it pointing to him being an ass-hat even as a kid it displays he has a certain lack of empathy. With these people or animals he truly couldn't care less about, they became playthings for his entertainment as he grew up, a habit documented and shown in several personality disorders starting at a HELLA YOUNG AGE. If you see your kid doing that nowadays, you take them to a counselor to have them get the treatment recommended by a specialist so they can healthily learn this behavior isn't okay and is problematic. But the spoon boi ain't living in 2018, and what do we know about the time era he's in?
His habits would be seen as nothing more than a boy being a boy, just small troublesome behaviors that help grow out of. And this may he turning into theorizing at this point, but let's turn to his parents now. We don't know much, but we see they're high class and have money. Now let's go back to the time era again. This is a time of booze and cigars, where domestic abuse was common and the rich flaunted their riches. I can see Vincent's parents wanting nothing to do with him outside of when they "need" him. He maybe grew up with a wet nurse, and the staff of his household were more or less more of parents then his actual parents were. But as the habits started to form, these figures couldn't discipline him as they weren't his parents, and I wouldn't put it passed kid Vincent to lie to his parents to make a workers day even more horribly wrong. So that would mean his ENTIRE upbringing was nothing but an echo chamber for his nasty habits, nothing to confront and correct his behavior before it became permanent.
But now you're wondering how or why his parents wouldn't have noticed this? That's the thing, most people with high functioning personality disorders are indistinguishable from the untrained eye as they can act completely sound of mind, unintentionally or intentionally. And after all those years growing up like that, he would have almost NO regard to authority outside of what he sets and deems in his own eyes, as well as people he'd see as people. The combination of his time era and socio-economic class is a HUGE factor with this as it basically made an echo chamber for the dinged little spoon boi.