You could argue that you only use your password on trusted websites, but:
- Even high profile companies and their websites can be compromised, thus leaking your password.
- HTTPS traffic can possibly be compromised when new and interesting security issues are found.
- Some websites do not even use HTTPS (including this very forum). Whenever you submit your password using a webform or browser-based Basic authentication method, it is essentially flying on the wire as plain text.