Your self-hosted WordPress website is your home on the Internet. It’s your own little slice of the Internet real estate, and just like any house you own, protecting it will fall squarely on your shoulders.
If you notice, I’ve specifically mentioned self-hosted WordPress websites. If your website runs on WordPress.com, then it’s not self-hosted. Securing your WordPress.com website is easier, in fact, you probably don’t need to think too much about it.