Many people hate Facebook, Twitter, Instagram, and various other social networks.<p>All have one concern and it is "Privacy", but bigger problems for these giants are, if they don't play with your privacy, they won't be able to survive today or in the future.<p>If you would be there, how would you build it? and What would you do?
Check out Tristan Harris, Adam Alter, Tim Wu, Jaron Lanier's writings. They have already spent many years thinking about where social media fucks things up beyond just Privacy.
I would probably build something that looks like activityPub/mastodon. Now, how you make it take off for mainstream appeal, I can't tell you. Probably make a client with a new feature the entrenched people don't (or even better, can't) offer you.