I came here because it has two things that I find absolutely essential that have become obsolete on popular social media platforms: long-form posting and a feed that displays the posts of people I follow in chronological order. I am, first and foremost, a reader, and I'm interested in reading extensively about what other people find important and interesting, which has more or less stopped being possible in the mainstream.
I've stayed because Steem offers an interesting array of tools for building economic structures - voting, autovoting, delegation, vote-buying, etc. - and I'm highly intrigued by the possibilities of what I can build with them. I've also stayed because I enjoy many of the people here and the generally deeper and less-hostile level of interaction.