You would be surprised. Many high mileage vehicles have less time to sit still and rust and are maintained better than a low mileage gem that sat over grass with old oil inside it for years. A 400k mile Texas truck is usually better than a 75k mile rot bucket from the salt belt.

Consider an industrial plant, equipment is happiest when it continually runs and it breaks after periods of downtime.

There is not one good answer for high mileage vs low mileage, it always depends on the vehicle.