Many expect intelligence, mediated by technological development, to be growing indefinitely. However to grow indefinitely it cannot be dependent on scarce resources such as those that define the complexity of the ecosystem on earth. An indefinitely growing intelligence needs to be driven toward new abundant resources, maybe in space, or on different planets.
If it were not driven toward new resources, and shared our limited ecosystem, then by definition it could not grow indefinitely. And if it should not be able to grow indefinitely, it would be exposed to suffer a Tragedy of the Commons resource depletion, just as we have… which would not be very intelligent.