The thing to remember is that all of the data collected and generated by advertising algorithms is connected to anonymous IDs which link up to Facebook accounts, and the data itself is usually complete gibberish as it's all binary data used by the systems involved. Nobody can take advantage of anything related to advertising to steal your identity or in any way disrupt your privacy, and the systems are falliable (I often get the most ridiculous eBay, Amazon, Reddit or Tumblr ads on Facebook because people send me links to disgusting content when get sweeped by advertising systems).
The people creating advertising systems don't give a stuff about you; it's all about the data proving they're doing their job so they can make a profit. Unlike the TV/Radio age where you can generalise and say "Oh we got a hundred million views" without accurate reporting (there's no way to know how many individual members are engaging the same or multiple devices since they're one-way signals), the companies who pay massive bucks to advertise are a lot more stingy in where their cash goes since online advertising can report hyper-accurate statistics, proving that this or that ad didn't get as many views/clicks as that one.
