<< People wildly overestimate how much other people care about them or their secrets.
People may not care about your secrets now. Right now you may be young. Right now you may have not pissed anyone off sufficiently to hire a private investigator to dig up stuff on you. Right now you may not be a party to a lawsuit.
All those things may be true right now, but things change. You have no idea how valuable right information can be at a given time. And here you are, volunteering it on a silver plate for anyone to pick as they please.
<<Nothing bad ever happened to me due to lack of privacy protection.
In other words, I think you are missing a key word here:"Yet". Nothing happened to you yet.
I would argue you have so much more to win, than you have to lose, from letting go of that fear to share your life online.
I am not sure if it is fear though. I personally feel I already spend way too much time online as it is. It was beyond awful as I was going through school, where I ended up doing work/school/fun by effectively just switching screen throughout the day. After years of that pattern I eventually severely cut back ( and even now I think I am overdoing it, but baby steps ).
I am ok with losing some people and some of the artificial online relationship that brings ( I accept that some online relationship may actually be stronger than generic RL ones ).
And while I'm diametrically opposed to the "if you have nothing to hide" argument, I really don't have anything to hide, so individually it doesn't impact me.