I am in the midst of a discussion with someone who feels very confident that an electron is always and forever a point particle and never a wave; any wave-like behavior that is observed must be attributed to a pilot wave that guides the path of the electron. I have sought to argue that this gets us into the question of the interpretation of what's going on under the hood in quantum mechanics, and that all successful interpretations that have survived give the same predictions and are empirically indistinguishable, effectively speaking (apart from the corner case of quantum non-equilibrium). My position, then, is agnosticism about what an electron is. My discussion partner has countered that the Penning trap is an example of an experiment that shows that the electron is a point particle and that the elementary charge cannot in any reasonable understanding be spread out over an extensive electron wavefunction. What assumptions go into this reasoning? Does he have a point, or is he overlooking something?