“Even if your profile is set to private,” said Ron Schlecht, managing founder of cybersecurity firm BTB Security, your likes, tagged photos, and other details, “can be made available to people who are not your friends or outside your social network.
“Some people try to hide by using a fake name or persona on Facebook. But the cellphone number or email address they used to authenticate themselves is connected to all that data, said Schlecht.
That personal identifier can then be connected by data brokers to other sources of your data and reconnect your profile. So while you might be hidden from your old high-school boyfriend or boss, the data miners can still find you.

Source: Is it possible to ‘safely’ Facebook anymore?
I am in process – a long process – of gradually deleting old posts and likes. This will be a long process as Facebook makes it very hard to remove old data, to the point of being nearly impossible. I just  deleted a handful of photos of family members, including me, as I no longer trust FB to have possession of such data.
Facebook’s business model has been to trick us – the users – into turning over precious personal information, then re-packaging that and selling it to third parties for the purpose of propagandizing us into purchases and political choices.
Facebook uses numerous tricks from psychology to hook us into posting, liking, sharing – and integrates that data, via our phone number, with third-party databases, including offline “loyalty card”: purchases at retail stores. The degree of invasive-ness is extreme.
They suggest this data is used for our benefit, but that is false.
In fact, a specific example shows how the data they collect is used against our own interests. Facebook, Google, LinkedIn enable the posting of job ads targeted by age. Nearly all employers uses this feature to specifically excluded older persons from seeing any job ads at all.
This is an example of Facebook using the collected data against our own interests. Facebook is – basically – a truly awful company who, by their actions, are on their hands and knees pleading for heavy handed government regulation.