The longevity of gravel tires all depends on the rubber compound that’s been used and where the tire is mostly ridden. Tires designed to be ridden off-road tend to be made from a softer rubber as this adds comfort and grip on uneven surfaces; the flip side is they wear fast and roll slower when ridden for long durations on tarmac.
As mentioned earlier it really depends on where you’re riding most, but selecting the right tire for the job will not only boost performance but it’ll increase longevity too.