BuddyPress.org

I’m not sure what you did exactly to make this so broken, but I can tell you how I did what you’re trying to do.

1. Copy “buddypress-home” theme to a temporary folder.
2. Rename “buddypress-home” to “buddypress-user”.
3. Delete “buddypress-user/home.php”.
4. Open “buddypress-user/style.css” and at the very least, rename the theme to include something with the words “User Theme”
5. Upload this theme, and activate ONLY it in your admin panel.
6. Make sure that theme is the ONLY active theme. This ensures users will only get that theme provided to them at default.

That should do it.