Well, means matter, as the saying gos: http://www.hsph.harvard.edu/means-matter/
People commit suicide opportunistically, not (generally) in a planned-out way. So it makes sense that Democrats, who favor government interference in life choices for the greater good, support something that reduces your opportunity space for suicide.
Of course, Republicans also support government interference in life choices for the greater good, just for different things (abortion, birth control access, sexual health education access, etc.). Really, it doesn't matter whether the beliefs are consistent, because nobody really thinks about this and few if any people who are debating gun control bring up these topics.
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.