Actually, with manufactured equipment generally (this is not specific to pools) the highest rate of failure is when the equipment is new; then the failure rate drops off to follow what's sometimes called a "bathtub curve", and gradually increases until the equipment approaches it's life expectancy.

If

(a) your heater works well this year, (spring and fall) AND
(b) you protect it from the weather over winter, THEN

it will probably be OK next year.

Moisture and bugs kill unused heaters. So does poor water chemistry.