Even amongst each other, they're completely self-serving: their motivations are more-often-than-not born from their own selfish interests, they don’t care to exhibit kindness to anyone in their lives in an attempt to reach their goals, and they’ll fuck over anyone they need to in order to act on every terrible whim they conceive, often resulting in the Gang destroying the lives of anyone who crosses their path (and being hated by (almost) everyone they encounter). Yet despite insane motivation, they rarely accomplish the menial goals they set out to achieve—the comedy lying in the fact that their actions are not only terrible, but an incredibly stupid, destructive way to attempt to meet their means.
Sunny is a black comedy because their characters continually fuck people over in the most reckless, idiotic ways possible and they manage to make their own circumstances worse in every attempt to get ahead, but digging into the lives of the Gang reveals something much more tragically dark than the terrible schemes we laugh at on the surface—because it’s not just that they don’t care about what they’re doing (as that’s sometimes, provenly not the case at all), but that they’re such broken people they’re almost completely unable to recognize that their behavior is extremely dysfunctional.
The multi-faceted aspects of their dysfunction is buried in the core of almost every episode, for each character in many different ways, and as you come to learn more about the Gang, it becomes increasingly clearer as to why they continue to stay together, trapped in their own miserable cycles of abuse—because it’s all they’ve ever known and all they’re willing to understand (consciously or subconsciously, as each case greatly varies, yet almost always linked to past trauma).