Ello, there's a lot coming your way, if you do well. The big social networks will compete with you, try to crush you. Users will badger and blame you. Press will misquote, villianize, and oversell you. Governments will threaten and pressure you. Mysterious forces will DDoS you and hunt your users' data. Well-meaning(ish) assholes will announce your security flaws in public. Enraged people will publicly claim you're a CIA, NSA, or FBI front company. Moles will try to work for you. Downtime will threaten you. Actual mentally ill people will threaten you. Toxic communities will blame you for their problems. Media will blame you for your toxic communities. The code won't scale. The revenue model won't be quite right. The hosting will be problematic. People will blame you for bigotry, hate, and even aiding human rights abusers and criminals.
...and that's just what happens if people love you.