TL;DR
Good 🎉
git config --global core.excludesFile "${HOME}/.gitignore_global"
OR
# .gitconfig [core] excludesfile = /Users/hiroga/.gitignore_global_global
Bad 👎
git config --global core.excludesFile "~/.gitignore_global"
OR
# .gitconfig [core] excludesfile = ~/.gitignore_global # OR excludesfile = ${HOME}/.gitignore_global
Environment
$ git --version git version 2.32.0