I don't agree with your reasons for deleting your account. I think it's unsubstantiated.
Think about the dilemma SE employees would be in, if they were to take your Question seriously. They can't say, "Oh, yeah! That's right! You should be VERY concerned about all the hackers getting every juicy bit of information about your life here on SE because we are so insecure and hackable here. So, we've made deleting your account as often as possible as easy as possible. Here's the FAQ we update daily on precisely how..." No sarcasm intended; they would have to say something somewhat along those lines in order to help answer your Question for the reasons you stated.
If "privacy" is your concern, there should be other ways to handle your underlying problem:
- Don't link social accounts
- Don't give information about yourself (which is unusually easy on SE to not give)
I would normally add, "Opt not to enter your credit card," but there isn't even an option for that on a normal profile.
Of all websites with "privacy" issues, I don't think Stack Exchange is at the top of the hacker's list because there just isn't much there to get.
But, I don't even identify with your concern because, as my username shows, I'm not afraid to tell the world who I am when commenting on their wisdom, work, curiosity, and research.
I can't speak for the many high-reps who remain anonymous (fine by me), but they don't seem concerned about deleting their accounts as a way of protecting their privacy. Maybe that's your answer. Or, maybe your question is better asked on IPS, "How will people respond if I want to delete my social accounts often?" or LifeHacks, "Is deleting my SE account on a routine basis the most efficient way to maintain my privacy?"
I think, maybe you're overly worried, and now, as your OP thread says, you're concerns are affecting other people.