How do people find out locations / identities from photos with barely any info in them?

Was reading [this thread](https://www.reddit.com/r/IAmA/comments/9li9n/i_won_a_30_million_lottery_jackpot_and_have_spent/) about a lotto winner and how just posting a picture of his living room, people online deduced his identity, even though he wiped the EXIF data from his picture.

Was wondering how that is even possible?

find identities people photos privacy