We can also ponder about the true existence of reality. Do we really exist, or are well all non real and in someone or somebody's head. Neither of which will ever be provable, but we obviously default to "yes we do exist" because it's simpler.
Many Worlds is falsifiable. It's making testable claims about how amplitude flows between configurations and recombines constructively and destructively. If we ever find an experiment in which amplitude is flowing by some rule other than Schrödinger's equation, we'll have falsified Many Worlds, and we can throw out the theory. Not all consequences of the theory are testable, but that's true of a lot of theories.
We can also ponder about the true existence of reality. Do we really exist, or are well all non real and in someone or somebody's head. Neither of which will ever be provable, but we obviously default to "yes we do exist" because it's simpler.