It's been recurrent when I hear people saying that AIDS doesn't exist. When I ask why, they give weird reasons like HIV is a virus created to control economy and to develop medicine, etc. Also when I try to watch videos on youtube about people that are infected with this virus, I see a lot of comments saying that AIDS is a lie and some of them base their opinions on a documentary called House of Numbers. So I would like to know scientific reasons if this a myth, or why this is true.
I think no one can really deny the existence of HIV or AIDS, just a search on google scholar will show >1,500,000 hits for each of those terms, and ask (hopefully any) doctor and they will say it does, though AIDS denialists do debate whether HIV causes AIDS. This paper explains the process of HIV causing AIDS. Further, AIDS denialists have not offered up well supported alternatives as to how AIDS arises without HIV being involved.
I think however that there is more debate fuelled by conspiracy theorists as to how the disease came about. This article from TIME magazine on conspiracy theories is a short piece about it, there are two main conspiracy theories:
1) The west invented the disease to "decimate the African population."
2) The US government invented the disease in the 70's and injected gay men to stop the spread of homosexuality.
You should read this section on the critical response to the film House of Numbers, it seems to be thought that the film was driven by funding wishing to promote conspiracy theory and interviews were edited in such a way as to help portray that message.
Caution, the following is my own personal opinion ;)
To most these seem like pretty outlandish claims and most people do ignore them - apart from anything, placing blame on someone won't stop the continuing spread of this horrendously devastating disease so the conspiracies are quite pointless. I personally think these conspiracies are driven by the uneducated, the scared, and those who want to "bring down the man & corporate/capitalist western society led by a powerful minority" etc..
Back to the science: The people who discovered the disease (Dr. Robert Gallo of the National Cancer Institute and Dr. Luc Montagnier of the Pasteur Institute in Paris) along with the majority of the scientific community say:
"the virus jumped from monkeys to humans some time during the 1930s"
Molecular analysis of the genetic sequence for the virus supports the theory that the jump from apes to humans was around 1920-1930. Some other studies support the jump being made around this time though some estimate it to be a little earlier, this is due to estimated rates of mutation being used to calibrate molecular clocks.
I'm not sure if I should be posting this as an answer, but I think a very approachable and accurate account of the history of HIV can be found from Dinis de Sousa et al.. I agree with what has been posted above. On the theory that a picture is worth a thousands words, you might also introduce skeptics to the cryo-electron microscopy images of the virus (searching cryo-EM HIV will pull up plenty).
That said, hard skeptics would likely want discount the thousands of publications, studies, and plain old researchers who have studied the virus (myself included).
Also, for the record, viruses that are "created" by humans artificially in a lab do exist, practically by definition. I, and a great many others, make viruses with markers that make them easier to measure or see (such as fluorescent proteins). But given the time that HIV entered humanity, it seems highly unlikely that anyone had the technology, let alone the will, to engineer the virus as a bioweapon. Certainly SIV predates HIV, but the technology to make such modifications (or even of the basic players and genetics) to make a recombinant/chimeric virus simply didn't exist.
It is the unfortunate truth that viruses have been used as weapons of terror and warfare against various populations (I could get into examples but that seems off topic). But the historical examples we have of this are all surrounding existing viruses.
To the question of people made to make money (not withstanding all of the above), it is certainly not for lack of trying that we don't have an vaccine for HIV. There are a lot of complications (extremely rapid mutation and escape mutants, reservoirs of virus, direct infection of cells from your immune system, etc etc). And it shouldn't be seen as though HIV is the long lasting human virus we need a vaccine for (Herpes and RSV just two good examples). You would stand to make a lot of money if you could successfully make a vaccine to any of the pathogens. And a LOT of people are trying. The US government alone is spending a lot of money on HIV/AIDS. Having a successful vaccine could actually SAVE a good deal of money.