I think you just said it yourself. They gave the company millions of dollars, and now the company is more loyal to them than you. The job of the company is to serve it's shareholders. At first, as a founder, you are the only shareholder. When you take investment, you are bringing in more shareholders. Sometimes you have to bring in enough shareholders that you aren't the majority anymore. But if your choice is to do that or have the company die, then you choose to give up control.
Workers are rarely given any form of control to give up when looking at investors, is my point. Really, the only relationship between investors and workers (as opposed to founders) is that whatever equity the company might give workers is eeked away by investors.
Mayharm says "the reason the workers give up control to investors is to get hundreds of millions of dollars".
The workers "give up" (if they have any say in it) control so that the company gets that money, not them.
I'm just saying that's not really the case, and it shouldn't be seen as any real quid pro quo.
I think you two are mixing up founders and employees.
It would be immoral for a founder to leave the company to start another one after taking in investors money promising them he will work hard.
It would be immoral for an employee to agree not to take commercial and technological secrets when leaving the company and sign non-compete agreements, and then do exactly that and found a competing company.
It would not be immoral for the employees to leave with a few colleagues to start their own company, but it would be immoral for the founder if the founder were to join them.
It would be immoral for employees to stop attending the office and stay home to work on their own startup while accepting a pay check.
Workers give up control to investors when the investors can give them the certainty of a pay check next month - because having control yourself means you must forgo the certainty of income in the short to medium term. This is valuable to people with debt and no savings (graduates and people with mortgages and families).
Workers don't like to give up control if they don't have to, that's why there is a proliferation of startups in Silicon Valley, and wages for software engineers are very high compared to many other professions.