The user data in question was collected legally in accordance with Facebook policies and user settings. That the database was transferred to Cambridge Analytica was a mere developer agreement violation.
But this was not a breach or leak. It was an exploitation of Facebook's own rules.
You know the phrase "knowledge is power"? In the 21st century, data is power, and whoever controls it writes the rules.
This is the web we implicitly agreed to without understanding the trade-offs. It's mostly been okay before now. It never was.
Even the most altruistic companies want your data. They might but sell it, but they will use it.