One

You can. But you cannot just clone what already exists and expect everyone to flock to it. You need to create new improved features that attract new users. Saidit did not improve on reddit and with lazy or compromised admins who were willfully disinterested in even keeping the app updated, saidit ended up being less than reddit as far as functionality is concerened.

To attract new users from reddit they could have introduced inline embedded video and images like twitter or telegram but without character limits. Built in language translation, securely encrypted direct messages and encrypted chats and proper user profile pages but they offered nothing new so people go where the latest features they want or need are at.