Conspiracy theories cannot be entirely discounted (Just as Russel's Teapot cannot be entirely discounted), but I haven't seen one that was developed on the internet and that actually held water for any amount of time. the problem I have is that conspiracy theories are not "Theories" in the scientific sense, and they sure as hell aren't investigations in the criminal sense.
I understand why many people think these conspiracy theories to be so compelling. It's certainly more comforting to believe in a big evil conspiracy that is out to get you, your freedom and your guns (not necessarily in that order) that orchestrates events to further their nefarious goals, than it is to believe in the possibility of people doing random **** out of their own volition. Being able to tie everything into a neat little narrative, that's always good; Admitting and being okay with the fact that sometimes things happen that just don't make sense is much harder than that.
Admittedly, I am biased against the whole subgenre of american conspiracy theories that follow the "Government does X to use as a precedent for tightening regulations on Guns/passing laws designed to broaden the powers of the executive" narrative.