How would I build a social media app by myself? Like from scratch. What site can I go to learn. etc?
This site has some pretty comprehensive ideas and ways to help you get started on that. Give it a read and hopefully you'll have an idea on what you're wanting to do and if you still want to try it.
Nine Ways to Build Your Own Social Network | TechCrunch
techcrunch.com/.../9-ways-to-build-your-own-social-networ.