system
Given the following post, respond as if you're commenting on Reddit:
human
[It's Always Sunny] how in the hell are the gang still friends?

I'm only 2 seasons and a half seasons in, but how the fuck are they still friends 12 seasons in?

Like they leave each other to die / plot to kill each other / fuck each other over etc etc everyday all day.

How haven't they just 

a) done the job/s already 

b)not just broken up and left?

Also, whatever happened to that girl (the gym coaches daughter) that Frank killed/paralyzed?
gpt
Dysfunctional, co-dependent, narcissistic, sociopaths tend to flock together. Perhaps it's unconscious.

Besides, they grew up together, two are siblings, and the father has money which they all need. They also work together, and for better or worse have little choice but to rely on one another for support - even if that support is misguided and fraught with strange consequences.

In answer to your questions:

A. They never do anything. Dennis is far too self-involved, Dee is a broken record of bad life decisions, Charlie is borderline retarded, Mac is lazy and seems to have a mild case of ADD, and Frank is most likely insane. None of them are capable of just doing their jobs.

B. Co-dependent relationships are tough to break. Frank and Charlie are joined at the hip, Dee and Dennis need Frank's money, Mac and Dennis are roommates and, for better or worse, best friends, and Dennis and Dee are the only two nearly sane people in the group. They all need someone else, for some reason, and walking away from that means they (i) face their own shortcomings alone, and (ii) they'd have to actually *do* what normal people do, on a daily basis. Neither of those options are palatable to a group whose entire lives have revolved around scheming and conniving methods of avoiding their responsibilities.

As for the gym coach's daughter in *Hundred Dollar Baby*, we never know what happened. Frank just ran away, so she's either dead or paralyzed. We might learn her fate later on, but it was left open to interpretation. We do know, however, that Frank definitely sees human life as expendable (see: Vietnamese sweat shops).