Too many people come to Wikipedia in order to change the world, to set things right, to tell The Truth about something. I think it's one of the root causes of dissatisfaction among new editors, and one of the things that sets some people on a course to consider themselves an enemy of Wikipedia.
Wikipedia's policy of Neutral Point Of View (NPOV) is an explicit statement that Wikipedia is not out to change the world's opinions. Some have even stated that it's Wikipedia's true innovation, differentiating it from other encyclopedias and reference works. Wikipedia does not attempt to judge the truth of anything; instead, Wikipedia reports accurately on what the state of current belief is.
If there is disagreement, Wikipedia gives space to all sides in proportion to the prevalence of each. (This latter is the prescription against "Undue weight", and is what differentiates Wikipedia's NPOV from journalistic even-handed neutrality. Wikipedia does not have to give equal time to members of the Flat Earth Society against scientific consensus of Earth's rough sphericity.)
Wikipedia doesn't care if you think you know the Truth or even if you can prove it—unless that proof comes in the form of solid citations to respectable sources. This, I find, bothers people who are sure they know the Truth about a subject—any subject.