Being contrarian is hip. Much like the counter culture of the 60s, disagreeing with the "establishment" is an identity thing, a way of trying to make a difference. Whether it's effective, or even reasonable, is not of consequence.
It's easy to make claims against a technical and scientific acheivement based on common sense and appearances. Add a political agenda to add "credence" to your arguments as icing on the cake. (being anti USA is kinda accepted today).
Then throw in a healthy dose of basic ignorance. TV and the internet give us tastes of many experiences..spaceflight, crime investigation, crabbing. We take that tiny exposure and assume we have a real good grip on how these thing really work, how it's done. We don't recognize the lens as distorted, and not all encompassing.
So, now that we "know it all", we can develop various viewpoints and assumptions, and arguments about the subject. The fact that we really aren't "experts", or even very knowledgable on the subject, doesn't matter. We saw it on TV, the Interner, the Movies.
Real knowledge, developed in an education somewhere beyond highschool and Liberal Arts, doesn't count to the shallow thinker. The intricate, detailed knowledge and experience base of the experts is seen as superfluous in the argument.
Some things require a decent knowledge base to argue, and many just don't wish to gain it. Some know little if any, and assume that what they know, or can "see", is sufficient.
There seems to be no stigma against blatent, proud ignorance these days.