The best action a disgruntled employee who can secure another employment can do is to leave. This is not the only the best choice for the employee, but also the mostbest way said an employee can cause pain to the business.
After you leave, you find better work, and then you are in a position to help your former co-workers move to the better company with you (although make sure that you are not under some anti-poaching clause from your contract). And if your assumptions about how the company is mismanaged are true (which is a very big IF as your perspective as a rank employee is extremely limited, and there should never be much stock put in office gossip), eventually the company will either change, or will struggle to keep the workforce needed, as employees will retire/move on, and finding replacement will be harder and harder due to buildup of reputation.
And if you are wrong, you will be happier in your new job and that ends this chapter of your life. Rather win/win I would say.
Since you stated that you can rather easily find new employment then I strongly recommend that you take that step. The more radical actions, like trying to arrange some sort of quasi-union will require a lot more time, planning and education on your part. Starting with not using company resources and time to facilitates such meets. Otherwise, you are trying to gamble not only with your, but also others work security, and that is simply not something you seem entitled to do.