So don't build on FB and Twitter? You do realize you can build an application and very easily host it for the world to access on AWS/GCP/Azure - unless you're doing something illegal or highly unethical the cloud services aren't going to kick you off. It sounds like you're saying you want to build a social media app but you don't like the fact that social media is dominated by a handful of companies (because the majority of users want to use their product already).