If you have traveled before, you know traveling can be expensive, especially if you are traveling overseas. Plane tickets, cruises, and hotels all can be very expensive, and in the event that you cannot go on the trip for medical and other reasons, travel insurance will reimburse you for the tripsite expenses.
For instance, my wife and I just booked a 15-day cruise to Europe. While we are very excited about this trip, it was very expensive ($5000+), and travel insurance to protect us was only $200. If we did not get travel insurance, and I broke my leg and was unable to go on the trip, we would not get any money back from our cruise company or our airlines. Travel insurance protects you in the event that you are unable to go on your trip for the unexpected.
Travel insurance also covers a lot of other emergencies you may encounter while abroad, such as lost luggage, health issues, legal issues, and other tough situations that most travelers never think will be a problem during their trip. I know of one traveler who came down with pneumonia while on a cruise. She had to be hospitalized on shore, and was unable to take the cruise ship home. Her travel insurance company took charge of her medical care while she was in Mexico, paid all of her medical bills, and then purchased the tickets to fly her home once she was well enough to travel again.