Maybe, but this is the exact opposite of polymath's claim- not that fighting a modern state is so difficult as to be impossible, but that fighting one is sufficiently simple that starting out without any weapons is not a significant handicap.
(The proposed causal impact of gun ownership on rebellion is more guns -> more willingness to actually fight against a dictator (acquiring a weapon is step that will stop many people who would otherwise rebel from doing so) -> more likelihood that government allies defect -> more likelihood that the government falls. I'm not sure if I endorse this, but polymath's claim is definitely wrong.)
(As an aside, this is historically inaccurate: almost all of the weapons in Syria and Libya came either from defections from their official militaries (especially in Libya), or from foreign donors, not from private purchases. However, private purchases were important in Mexico and Ireland.)
but that fighting one is sufficiently simple that starting out without any weapons is not a significant handicap.
I didn't claim that fighting a government is simple. My claim is that the hardest part of fighting a government is forming an organized militia with sufficient funds and personnel. If you manage to do that, then acquiring weapons is probably comparatively easy.
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.