An excess of science will leave none of us alive. - R. A. Lafferty

Persons such as Isaac Asimov and Carl Sagan say that tens of thousands (maybe tens of millions) of planets will fulfill the conditions for the support of life. And then they take the rather deceptive step from the ‘possibility of life’ to the ‘inevitability of life’ by such connivance as would shame a crooked gambler. They posit towering numbers of ‘civilizations’ on those ‘possibility-of-life planets’, at least half of them to be more advanced than the Civilization of Earth and Humankind.
But there is a strong element of Advocacy Science in this. There is a great and powerful lobby advocating the existence of great numbers of superior civilizations. One reason for this is that the secular-liberal-agnostic-relativistic faction of scientists cannot allow the uniqueness of anything, not of Earth, not of Life, certainly not of Human Life, most certainly not of existing Human Civilization. To allow the uniqueness of any of these things, they would have to cease to be secular-liberal-agnostic-relativistic persons. And the shock of changing their style would kill all of them.
Science Fiction also has a vested interest in there being a multiplicity of inhabited worlds and civilizations. That is one of the small number of things that Science Fiction is about. But Science Fiction is, after all, only a fiction.

I do not understand your custom in this, but we do not intend to fight until all of us are dead. We desire very much that none of us be dead. And we will fight till all of you are dead only if it is absolutely necessary.

The historian Cassiodorus believed that the selective destruction of Alaric, as regards the Greek monuments, was of good effect. Alaric had some taste and was awed by really great art. The Greeks were only human, and all their work could not have been excellent. But almost all their ancient work that survived the ravages of Alaric was of unsurpassed excellence.
There is abominable and worthless ancient Greek art in Asia Minor, in Constantinople, in Thebes, in Eritrea, in the Cyclades and other islands. There is little or none of this worthless ancient art surviving in the path of the Gothic Greek adventure; not in Athens, or Megara or Corinth or Argos. Sparta does not figure in the account at all; it never had art.
It is said that Alaric destroyed half of the art of Greece. It may have been the worst half. He was a critic of unusual effectiveness.