ssh returns "Bad owner or permissions on ~/.ssh/config"
If on Windows Subsystem for Linux (WSL) and you pointed your WSL home directory to your Windows home directory (not recommended!) then chmod has no effect. Before you can chmod the files mentioned in other answers you must add [automount] options = "metadata" to your /etc/wsl.conf then restart WSL (requires build 17093 or later).
https://serverfault.com/questions/253313/ssh-returns-bad-owner-or-permissions-on-ssh-config