Reasons people believe in conspiracy theories:
-Policy in exact opposition to libertarian political ideals. Would expect to see a more random dispersal of policy if there wasn't an overarching ideology behind political decisions.
Or it could be the case that, without any deliberate conspiracy, those wielding power are rarely interested in policies that reduce their power.
-Both political parties have, for the most part, identical policy. This implies something else affecting both.
Or it implies (as above) trends in any form of government such as pressure towards plutocracy. It's all we can do to hold it back even slightly, it requires no conspiracy to drift in that direction.
-Sheer draconian nature of recently adopted/proposed policy (Patriot Act, New Deal, wiretapping, DARPA, existence of CIA/NSA, etc.) Loss of privacy, economic freedom, civil liberties, choices, etc.
Can easily happen naturally just from citizen apathy combined with political ambition.
-Mainstream media sources constantly and deliberately omitting important information that would surely get excellent ratings. (so profit motive can't be the explanation for the absence of such information) Proliferation of mind-numbing, utterly stupid entertainment financed by powerful groups.
Examples are needed to evaluate this claim more fully, but if I were to speculate I'd say this "missing information" ranges between unreliable, uninteresting to their targeted readership (as tragic as that is), or embarrassing to their advertisers or owners. Again, no conspiracy required, just self-interest.
-Conspiracy admitted and talked about at length by politicians, businessmen, thinktanks, etc.
Examples needed for better evaluation.
-Government response to problems are ineffective/immoral and it is unlikely that government is unaware of the ineffective/immoral nature when any lowly person with a computer can be made aware. Basically, government incompetence is an invalid explanation for poor policy.
Never underestimate the power of stupid people in large groups, or (I shall add myself) the stupidity of powerful people in groups.
I wish I could believe that power can be expected to correspond with competence, but I've yet to find good reason to think so.
-Economic system benefits the few and the world economy has become increasingly monopolized by fewer and fewer multinational corporations. People wonder how so few can control so many - at the root, its done with the power of money.
That those with money have undue influence is well known... and that such interests desire further consolidation is also clear. I'm not sure where such requires a conspiracy, since without any collaboration they may behave just the same manner.
-The things most of us consume, because they are made economically convenient, are almost invariably harmful to our health. Some things harmful to our health are understandable with no conspiracy necessary, but when the powerful, global corporations are always the suspects combined with the fact that creating toxic consumables is not originally economically viable. Basically, toxic consumables have been incentivized through subsidies, the FDA, and various other means.
Which toxic consumables, for example?
-False flags with ample evidence
Examples?
-All of the above in direct, precise opposition to what is taught in public schools and professed in the media.
And no other reason for getting bad information in schools and media, than deliberate conspiracy?
-Its really not too hard to read the documents of secret societies. There are entire religions and belief systems that are truly stranger than fiction and answer the "why?" question for a grand conspiracy. Most of these the common person knows absolutely nothing about.
So... because it doesn't have to make sense, it must exist because even nonsense could be the reason? I'm not sure I follow.
-Symbolism (related to the above point; exists in too great a quantity to be coincidence)
Symbolism is easy to find even among unrelated or only roughly related elements if you're looking for it.
-The existence of internet shills. Visit godlikeproductions.com and maybe you'll see what I mean. Too important information on many sites gets sent down the memory hole...
-The existence of the more bizarre and patently false conspiracy theories like bigfoot, moon landing hoax, etc. are interestingly focused more upon by the paid-for mainstream because they are easy targets and serve to discredit conspiracy theories in general. Again, follow the money trail.
I like this one--attention to bad conspiracy theories mean that the good ones must be true!
-Intermarriage between those in power in greater occurrence than what is accounted for by mere coincidence. Most politicians run in the same social circles and are related by blood.
Again, doesn't require comprehensive conspiracy, as demonstrated by your second sentence there. Money and power likes to marry money and power.
I do not dismiss these points as obviously false or unimportant--only show where they may fail to convince.