> Why does the government need so much data on its employees; that's what should be asked!

I don't know if you had to get a clearance or not, and if you did, what kind. But assuming that you did get a clearance, they need all of this information because they need to build up a psychological, emotional, familial, and financial profile of you to determine how much of a risk you are. At least, that is what the government will tell you is the reason why they investigate you so much.

You can request a copy of the investigation the US government performs on you (whether you are a government employee or a contractor with a clearance) through a form you can find on the website of the Office of Personnel Management. Although, hilariously, they will censor some of the information about you that they find. That is a window into what their thinking is, because you see who they talk to, what questions they ask, and how people responded.