We do know the motivations to some degree because they're constrained by physical reality, evolution, and game theory. Von Nuemann probes are possible in this

We do know the motivations to some degree because they're constrained by physical reality, evolution, and game theory. Von Nuemann probes are possible in this physical reality for a relatively cheap cost and small time frame. It makes sense to put probes that can watch for threats anywhere you think that threats can be. Species that do this have a greater chance of survival than species that don't.