Not only are you legally obligated to buy auto insurance, you should buy car insurance to give yourself peace of mind.
There are three reasons. The first is that a minimum amount of insurance is required by New Jersey law, and in virtually all other states. The second is buying insurance is smart. For most of us, our car is the single greatest source of risk in our lives. Because driving is such an integral part of our day-to-day experience, it's easy to forget what driving actually entails: conveying a steel box at high speeds filled with explosive liquid, and on roads filled with other such vehicles operated by other very, very fallible human beings.
More than anything else you own, your car is by far the most likely cause of significant injury to yourself or others, and the most likely reason why you'd be sued for significant sums of money-in most cases far more than you'd be able to afford. A sound principle to abide by is to only risk what you can afford to lose. For the vast majority of people, the type of losses that are commonly the results of car accidents represent risks that are too great to assume themselves. Nobody wants to be a victim, and buying insurance soundly is one of the best means of ensuring that this doesn't happen.
The third reason is a matter of our duty as responsible citizens. Insurance isn't just about protecting ourselves. It's also about protecting others from us. We all make mistakes, but, unfortunately, driving means that seemingly minor errors-momentary lapses in judgment and attention-can irreversibly alter another's life, and even end it. I believe that we must be responsible for our actions and accountable for our mistakes. Buying insurance is the best means of ensuring that we are able to take full responsibility for any mistakes we make on the road.