The problem is that you can't unilaterally decide "I'll do my 9-5" when everyone else is doing something else, there'll be ramifications to your career one way or another.

That's why you need unions, to make things like this collective action.

Or just find a job that you're good at and where you're happy and stop running after promotions?

While I agree, I do think that that is a small minority at this point. I just broke into the workforce after college 5ish years ago and I never had this mentality. All of my coworkers around my age are the same, we know the company is only loyal if it's beneficial for the company. Some younger people in the workforce have these pied eyed romanticized ideas, but most of us have seen too many examples like this and are just jaded. I assume every facet of my interaction with society is someone trying to exploit me somehow, because that's almost always the case. I started feeling this way around 11th grade because the education system is in such a bullshit state, and college verified my thoughts with data. By the time I hit career age I knew it's fuck or be fucked out there and loyalty is only for family/friends. I am in a STEM field, science not tech, for reference.

They don’t teach you hardly fucking ANYTHING in college that’s helpful in terms of addressing the modern corporate profit über alles dynamic that most jobs have turned into. You just get thrown in the deep end with your diploma, and nobody tells you that the pool is actually part of a processing plant, and that the current is sweeping you along… somewhere. It might be to a nicer pool. It might be a separator machine that exploits all of your usefulness at an accelerated and unsustainable rate. It might be a waste outlet. It’s kinda impossible to tell when you’ve had zero fucking experience or instruction on “how companies ACTUALLY operate”, and how to effectively operate in that environment without walking face-first into spinning blades you didn’t even know existed.