If I had a list of rules of effective political advocacy, on that list would be that you should be able to know and argue your opponents position as well as, or better than they can. The left-leaning Vox.com runs an article speaking truth about who they are up against in the fight for more gun control, and I think they pretty much get it right.
But money alone cannot explain the gun lobby’s success. Members of the NRA and allied groups bring an intensity, volume, asymmetry, and geographic reach of passion that is rare in American politics. Until that is matched on the other side, the gun lobby will continue to win.
This is essentially why Bloomberg struggles for success, despite being able to outspend us. If the Democrats were supportive of the Second Amendment, even if it was just lukewarm, I could probably find better things to do on election days when I’m dissatisfied with the Republican choices on other issues (which I usually am).