one or the other or a bit of both:
about earth, there are the facts commonly accepted, about population, that there are billions, age, billions again, and so on. now it must occur to anyone who has ever experienced, either visually or audibly, what could be called "errors", that something is perhaps not quite right about the many assumptions people make. now medical science would have it that these "errors" are strictly those of the individual in question, so to speak, and not of earth itself or science. however, what if the fault does lie with whatever earth is and blame is not on the person's senses? inevitably, the more glitches in the system that appear, the more you become convinced that there is some huge electronic machinery at work underlying everything, a supercomputer that simply does not work perfectly.
by visual "errors", those that i have experienced personally, from most shocking to least, first of all, a sudden total change in place, to teleport to another location, secondly, less striking perhaps, but common enough, a sudden change in text, for example, looking at a printed train timetable at a railway station and the times change, thirdly, maps that are all wrong from what you know, fourthly, definite changes in books you have, on second reading, some passages have disappeared, fifthly, and often you cannot be sure about this, objects have been rearranged in the room when no has been present or they have vanished.
actually, the only ones who could firmly believe in all that the media presents about earth and what their teachers taught them in geography and science, the only ones who actually "buy it" are those for whom there are no discernible "errors", those who have supernormal lives.
it is all too easy, however, to dismiss all common scientific theories and leap to the other extreme, that all of life on earth is a vast computer simulation and perhaps therefore you are the only real person on earth and everyone else is virtual, if you like, non player characters or NPC's, illusions, philosophical zombies, etc. such is the nature of the beast when something happens that makes you question reality. it is most likely that neither extreme, the one of a densely populated earth where everyone is real and the other of the empty simulation with a real population of one, is true. it is not all or nothing, but a little of both.
it is interesting that the thinker always thinks in absolutes first or extreme positions. this may sound perverse, but often something may be true and false, even if only time and space make the difference. now it is true, then it was false! it is true here, but not there! define your terms! clarify! what i am speaking of is a tendency, perhaps almost a hope, to think that something would be true now, here and everywhere, for all time! that things contradict themselves moments later exposes this fallacy in our thinking.
what is the suitably complex, averaged world view? it is most probable that there are many people on earth but not as many as purported, and that some people truly are not real, they are part of the background simulation. there are questions about history too. if we assume the numbers prone to exaggeration, we would guess that the true age is much younger. when the first real person was inserted into the simulation earth is another question. note that to teleport rules out the whole model of classical mechanical motion in reality.