The hard truth about privacy and the Internet is - that there really is none. There may have been at one time, but not now, and there probably never will be again.
I won't even go through the litany of hacks, fishing, data disclosures and actual out-and-out spying that we see reported every week (and only guess at the ones that are not reported).
Just rest assured that if something can be hacked, it will be (if it's worth anything to someone).
So, should we just throw up our hands and give up? No, but you can do what you can to make things harder for the bad guys (actually, I don't know that I can even limit it to "bad guys", since our own government is apparently spying on us with impunity).
Use good passwords, keep your version of Windows or macOS up to date, don't fill up your smartphone with random apps, only what you need and use, etc. And personally, I would avoid Internet of Things devices for the time being, since their lack of security has just been astonishing so far.
Assume that anything you post online or email anywhere can be see by others, because it probably can. So don't announce to Facebook that your home will be available to rob for the next week, since you will be on a cruise...