Pournelle's Iron Law of Bureaucracy states that in any bureaucratic organization there will be two kinds of people:
First, there will be those who are devoted to the goals of the organization.
Secondly, there will be those dedicated to the organization itself.
The Iron Law states that in every case the second group will gain and keep control of the organization. It will write the rules, and control promotions within the organization.
If you want to change the company from within then you are almost certainly dedicated to the goals of the organization and they are falling short, but it is loyalty to the organization itself that gets you clout. So in order to change the company, you first have to do the thing that you want to change, like cutting corners to meet a deadline. Only after you've kissed the ring will you be given power. This means that unless you are able to perform a revolution or coup within the company (maybe by unionizing), you will always be subordinate to its rotting fish head. If you want to change the company, the best way you can do that is by joining a competitor with better leadership and out-competing or being that leadership at a competitor.
Being a subordinate to people you don't respect is going to demoralize you, demotivate you, disempower you, and make you lose respect for yourself until you cannot function as a person.
If you want to make a change, your only option is to get into a position of power, be subject to the same corruptive forces as the incumbent, and choose to be responsible instead of selfish, which is fundamentally an act of self sacrifice. His discussion of the video is way more thought provoking than the original video itself, IMHO: https://www.youtube.com/watch?v=ILvD7zVN2jo
Attempting to do so is almost always a fools errand. Unless you have an outsized voice for your position then you will never actually turn a company around and attempting to do so will only add to your burden and worsen your situation.
It depends on your position and on the company. There are situations where you can have impact, in which case you should definitely use that. There have been plenty of cases where employees did seriously change corporate policies, but that's usually either in small companies or in companies where employees band together. And often the only impact you can have is to quit and take your skills to a more responsible company.
I've found (in <200~ employee companies) well structured exit interviews to be the best way to change a company from within. What better way to express your disapproval than by severing ties?
