How do you deal with massively poorly-performing and unknowledgeable teams?

For background, I've been in my current position for ~7 months now.

A new manager joined recently and he's just floored at the reality of the team.

I mean, a large portion of my interview (and his) was the existing manager explicitly warning about how much of a dumpster fire everything is.

But still, nothing prepares you for it.

We're talking things like:
- Sequential integer user ids that are passable as query string args to anonymous endpoints, thus enabling you to view the data read by that view *for any* user.
- God-like lookup tables that all manner of pieces of data are shoved into as a catch-all
- A continued focus on unnecessary stored procedures despite us being a Linq shop
- Complete lack of awareness of SOLID principles
- Actual FUD around the simplest of things like interfaces, inversion of control, dependency injection (and the list goes on).

I've been elevated into this sort of quasi-senior position (in all but title - and salary), and I find myself having to navigate a daily struggle of trying to not have an absolute shit fit every time I have to dive into the depths of some of the code.

Compounded onto that is the knowledge that most of the team are on comparable salaries (within a couple thousand) of mine, purely owing to length of service.

We're talking salaries for mid-senior level devs, for people that at market rates would command no more (if even close) than a junior rate.

The problem is that I'm aware of how bad things are, but then somehow I'm constantly surprised and confronted with ever more insane levels of shitfuckery, and... I'm getting tired.

It's been 7 months, I love the job, I'm working in the charity sector and I love the fact that the things I'm working on are directly improving people's lives, rather than lining some fintech fatcat's pockets.

I guess this was more a rant than a question, and also long time no see...

So my question is this:

- How do you deal with this?
- How do you go on without just dying inside every single day?

soo, i am unknowledgeable of ALL best practice.

lets say i call a php file called loader.php with a $_GET['type'] parameter, then after i check if type is actually set i switch the parameter and my logic then does stuff appropriate for $type..

do i create a lot of sub files with the program logic in it or do i just create subfunction (which i have to pass variables if necessary)?

Switch( $_GET['type'] ) { case 'foo': include "logic/foo.php"; break; default: echo "error"; break; }

or is the whole concept totally alien and stupid? i most honestly say that i dont know exactly what i could google to find an answer