Surely brute forcing would be impossible if you changed your password to one with a length of 100 characters that includes special characters.
Well yes, but most people don't do this. Most people use a short and easy to remember password, usually with a dictionary word or two, and reuse the same password (or almost the same password with minor variations) across multiple sites.
If you use a proper password manager, as you should be doing, and it generates a long and truly random password for you, then yes, brute forcing is next to impossible.