Insurance companies in the US never pay you the full amount to replace a stolen or a total loss vehicle. They pay ACV (Actual Cash Value), which is determined by the wholesale price of the vehicle at the time of the loss. That means that the mileage and age of the vehicle is used to determine the payout which is nowhere close to the actual replacement cost of the vehicle. The tracker will help recover a stolen vehicle and avoid the financial loss the car owner would face otherwise. A tracking device also lowers insurance premium considerably.
You will have to do your own cost benefit analysis. Consider the cost of installing a tracker, discount on insurance premium and the wholesale value of the vehicle down the road. It is usually a good idea to protect your investment, especially if your vehicle will be parked in an unsecured location most of the time.