Couldn't have said it better myself. I've managed to unintentionally break Ubuntu once
but it is so much fun to use if you know what you're doing.
This is where the separation between root and user can save the day, Never install anything outside the standard ubuntu packages system-wide (using root).
Install everything else in your user account, with your normal user account.
While it may break things in your account, the system will stay stable
But indeed, make sure the important stuff is backed up, and you can experiment all you want with the system. In my experience, it's horribly difficult until you get the point, and then you wonder how on earth you could not have seen that obvious solution