Have you ever had a flat tire?  Did it occur in a convenient place safely away from other traffic?  Did you ever have a breakdown partway through a long trip?  Many of us have to answer "yes...and yes" to these questions.  It certainly happened much more often when I was young and had a less reliable car but it still happens occasionally.

You need more than just the spare tire your car came equipped with.  Jumper cables, some appropriate tools, warning devices to make the scene safer for you, your passengers and the other traffic, some gloves and a flashlight are just a sample of what might come in handy if you have a breakdown either in town on a city street or on a lonely mountain road after dark.

The more prepared you are for emergencies, the less of an "emergency" they become.