At many levels the evidence would be, yes. At a global level, more human beings die to the violence or negligence of other human beings than due to any other earthly enemy. At an individual level, we have suicide, self-destructive behaviors, and lack of self-care. In between, there are all kinds of hurt and neglect at family, social, and societal levels.
But we must also ask: Are human beings our own best friends? And the answer would be yes. We dream of world peace, and work to make it happen. We solve social problems and eliminate diseases. We share love in our families and communities. We actualize our own potential, then create, share, and serve.