Many people find a vehicle that they like and drive it for a few years and when they are done with their vehicle they can simply trade it in for a new one. Some other people drive their cars for longer than a few years, maybe ten years or more, and then decide that they do not want to drive it anymore. Though it may seem economical at the time to keep the car for longer than just a few years, this can work against you because many dealerships will not take a car back that has been driven for more than just a few years and give you a new one because the car has been too worn down to be sold to someone else.
Less hassle, usually, then trying to deal with a private sale, since the company takes care of your paperwork, title, loans, etc. You usually get a short-term warranty or a money-back period to fix problems that become immediately apparent or if you change your mind. The rental company follows the manufacturer