Not because you have many followers on social media networks and think you are running a startup but you can develop a startup through existing accounts with many followers. Every startup solves a problem.
You can grow a community through your startup with the phrase "Share It" most especially when you have sharable contents on social media networks. Always encourage your visitors to share your content.
Stop trying to perfect your startup idea. No one idea was perfect at initial stage. It is until you start to work on your idea that it get a better look.