This is a very interesting solution to the Fermi Paradox. what is the most notable, is that it took so much time to get this proposition. But once you know it, it make perfect sense:

Any civilization don’t need to expand at all. Managing resource should allow you to live on the home planet without problem until the star goes supernova. At worst you have a plan to go to the next planet, in case of problem you cant solve.

So now… if we postulate such a civilization ( highly advanced and resource conscious ) What do they need to do to survive, that we can detect?