What is more insidious is that by itself some small portions of information are not private. But collectively they are.
Some portions of information seem innocent too like 'how much is in your account' could mean the difference between if someone tries to target me or not. Say I owe 500 bucks and have 10 in the bank and they may not bother. But say something like I have no debt and have a million in the bank and suddenly I am a very attractive target. That is for both 'good' and 'bad' actors.
Something as simple as giving your email to someone can tie you into yet another ad network. Which has already profiled you.
What is the worst of it is, I really do not care if you had the information. I do care if you use my information to mess up my life or harass me endlessly. So my default position is 'sorry I am not telling you that'.