What do you imagine when someone says "security"?
Hackers? Attacks? Defenses? A programmer in a black hoodie in a dark room?
When the word "security" comes to mind, it's usually in the context of bad news. You often encounter headlines like "A big social network leaked login passwords" or "an attacker stole credit card information from a shopping site".
But security is something to be taken as a positive and necessary part of web development just like "user experience" or "accessibility".