You put a lot of work into building your web site, making it look and perform exactly as you wish. The last thing you need is for some miscreant to deface it, take it down, or take it over. To prevent that, you need to be proactive.
This past week, security researchers discovered yet another major data breach, this one exposing more than 711 million email addresses and passwords. Even if all you do is send pictures of your cat to your friends, you need to secure your email.