Literally the point of a job at a for-profit company is to make money, yes, primarily for yourself and secondarily for the business. This is by no means moral or virtuous. But it is
true, and because it is true, the people who admit the truth of it will be more successful in the sense that they will be working with the system, and the people who act as if it is somehow untrue and there is some greater virtue behind it will be frustrated in the sense that they will never be able to work against the system enough to unseat it.
Why did the startup get acquired by the large company in the first place? To make money for the shareholders (mostly the founders), partly through an exit event, partly through the ongoing value of their shares. Sure, they wrote an internal email and a blog post about the "next stage of their journey" and how the big company "shares their vision" or whatever, but that's not the real reason - the reason is money. Why do employees get equity? To incentivize them to care about the money the company makes, because otherwise they wouldn't care sufficiently about the secondary goal of making money for the company (i.e., making more money for management, who sets the equity policies). Why do employers compete on salary in the first place? Because that's what being employed is about - making money.
If you want to do good work, to change the world for the better, to have fun, or whatever, you have two options. One is to secure your place within the system of being successful by making money - i.e., to show management that you will make them money if they keep you around and keep you happy - and then find some room to maneuver within it. There are a lot of people who are happy and fulfilled with their jobs because they can do this. The other is to leave the system (retire, work part-time, join a convent, etc.).
But refusing to admit the rules of the game will work about as well as trying to play a game of chess by bowling a ball at the pieces and knocking them down. You might say you don't care to win, which is fine, but that's hardly the problem - everyone involved, including you, will end up upset.