If you've been using internet for any extensive amount of time it's inevitable, it's not just about being "retarded", it has never been as serious as it is now. Leaks from sites you haven't thought about in 20 years. Forums that won't wipe accounts. Government and their contractors getting hacked and all their data being posted all over the place, or simply being incompetent and letting their documents being indexable. Scrapers for anything public you've ever put out. Most people weren't running different emails to sign-up to places, and it wasn't that obvious all of that, combined together and ready for consumption, would be available by just copy-pasting an email address, and even if you did and/or used some privacy service, you're bound to make some mistakes, slipping up, maybe because you were in a hurry to get something done instead of doing what would've been considered excessively paranoid at the time, if not just for spam prevention. Not much you can do about it other than not making yourself an easy target, if you don't have anything worthwhile for others to post about there's only people with an hateboner to worry about.