Be explicit about consequences of running as root

Author: Mr-Pepe

src/pip/_internal/cli/req_command.py

@@ -219,7 +219,8 @@ def warn_if_run_as_root() -> None:
 
     logger.warning(
         "Running pip as the 'root' user can result in broken permissions and "
-        "conflicting behaviour with the system package manager. "
+        "conflicting behaviour with the system package manager, possibly "
+        "rendering your system unusable."
         "It is recommended to use a virtual environment instead: "
         "https://pip.pypa.io/warnings/venv. "
         "Use the --root-user-action option if you know what you are doing and "