Doesn't pilot-wave QM imply literally the exact same calculations happening as for MWI, though?
No, it doesn't. Pilot-wave QM postulates an additional fundamental equation (the guiding equation) that doesn't appear in MWI. It describes how the behavior of the wave function affects the positions of particles.
Okay, so it does some extra calculations. But it still does all the same calculations as MWI?
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.