The most authoritative source of information on this would be the History Channel. If there are dragons, the History Channel will have documented it.
I think most people believe in this stuff. The question really is dependent heavily on culture and language - i.e. what is a “dragon”? Some people would describe any large lizard or reptile as a “dragon”, while some reserve the term for fantasy-type creatures. To make an analogy, lions are sometimes referred to as “cats” or “big cats”. At other times, the term “cat” is restricted to much smaller creatures and lions, tigers, etc. get classified as separate animals. Oh my. Language is weird.
FWIW, some Creationists use the parallel Western (large, fierce, fire breathing reptile) and Eastern (large lizard associated with good luck) traditions of dragon stories as evidence that humans have a primordial cultural memory of living alongside dinosaurs. The argument is that anything that goes back so far in history in so many cultures probably spread a very long time ago.
I’d say that “serpent” doesn’t literally mean “snake” but can also describe something more monstrous. For example, we already have sea snakes but if I was to say “sea serpent” most people would be thinking of something much larger and probably not shaped just like a giant snake but rather adorned with fins,a crest, a more dragon-like head, etc.
But anyway, I’m sure that even people taking it literally would mostly agree that “Satan taking the form of a dragon” doesn’t necessarily translate to dragons being real in the cryptozoology sense and an active part of the ecosystem. (Agreeing with your point no. 3)
In a similar vein, but directly dragon-related, there are the Dragon Holes of Hong Kong – the most famous of which is in the Repulse Bay apartment building – that exist so that the local dragons can easily get from the mountains down to the sea to drink and bathe. If such a building is constructed in one of the most expensive real estate locations on the planet, without maximizing the number of apartments, then that is a pretty good indication that someone – either the city planners, the architects, the builders or the residents – believes in the dragon-related aspects of feng shui. One has to assume that the belief is in corporeal (albeit perhaps invisible) dragons, rather than just “dragon force”, or else why would the holes need to be physically present?
Follow the money!
Our modern-day image is medieval in origin; the bible texts are much older than that.
(The same is true for our image of Satan, incidentally.)
As Nava has pointed out, the Greek word that is translated as “dragon” in Rev 12:9 (and elsewhere) can equally be translated as “serpent”, and indeed it is so translated in some English translations of the text. And the Hebrew word which is rendered as “dragon” in some English translations of the Hebrew scriptures is rendered as “jackal” in others.
I don’t want to hijack the thread with worldwide folklore but I do believe all such beliefs are related psychologically. Like I said earlier, I do not know of anyone that personally believes in dragons (other than proxies like Nessie or the Lake Champlain monster) but I do know people personally (in my family unfortunately) that believe in both Bigfoot and alien abductions. One of them doesn’t just have a casual agnostic opinion either, she travels to conferences dedicated to both subjects despite being a college educated professional.
The closest belief in dragons that I know of besides those mentioned before are people that still believe dinosaurs may still live in the impenetrable parts of the African jungle based on tribal reports and a few figurines that have been found.
However, belief in unlikely things is surprisingly strong among many if not most populations no matter how educated they are. My ex-SIL went to Nigeria to work with Mandrills (very large monkeys) on a preserve. One escaped and she had to bail him out of the local jail because the police believed he was a wanted criminal that turned himself into a monkey to avoid capture. It wasn’t a joke because they didn’t appreciate his deceit but they eventually let him go with the promise he would be closely supervised. It is an accepted fact in parts of Nigeria that witchcraft is a real thing and can be used to deceive others.
I wish I could help you more on the dragon specific part of your question but I don’t find it hard to believe at all that some people have and still do take the idea very seriously.
I personally don’t believe in dragons, elves or vampires but nobody is ever going to convince me not to be afraid of ghosts - I can handle physical threats but supernatural ones always freak right out.
Only if they were around during World War II.
“Anál nathrach, orth’ bháis’s bethad, do chél dénmha” 
Not even all European dragons were the same. Some had wings. Others did not. A dragon might have four legs or two legs. It might breathe fire, or fog, or poison, or just ordinary breath.
I’m not saying so much that dragons are real, only that biologically their is no reason one could not have existed.
Consider:
- Our bodies produce natural methane which can burn. Have you ever seen people hold a flame up to someones butt and have them fart and set the fart on fire?
- Nature has some bizarre animals. Take the bombadier beetle who’s body can spray acid. The skunk which can spray a nasty liquid. The electric eel which can shock its prey.
Looking at the above I dont think that its impossible for there at some time in history have been an animal who was capable of breathing fire. All it needs is a source of a spark.
If someone out there is better at biology than I am please tell me I’m wrong.
Hell yeah! 
Well that person certainly said it better than I did.
So does that make sense to the op? Is saying that one believes in dragons existing the same as believing in the possibility?
There are enough that books have been published showing how dinosaurs = dragons because humans and dinosaurs lived at the same time of course :rolleyes:
the book I saw even discussed how a dino/dragon might be able to breathe fire.
One of my fundie friends own this book.
They really aren’t the same. I find it highly unlikely that any human has ever seen a dragon that breathes fire and has wings.
See this thread: Where did the idea of dragons originate? - Factual Questions - Straight Dope Message Board
Point 3 is controversial, and was discussed in the linked thread. Point 2 provides an evolution of Western draconic folklore. Notwithstanding the claims of Peter Dickinson (h/t Tuckerfan), I’m highly dubious that any creature larger than a human that coexisted with Europeans could disappear without leaving convincing physical evidence.
Guns made dragons extinct.
Before, knights only had swords, lances, maybe a crossbow (bigger equipment like the ballista, catapult, and trebuchet were fine against a castle wall, but useless against something which could step/fly out of the way;)).
Ironically, with the great beasts now out of the way, kingdoms didn’t need knights in shining armor anymore; a knighthood became simply an honorary title with little or no practical application.
:rolleyes:
Grand?
Also, jtur88, I believe this “If there are dragons” should always be rendered as “If there be dragons”.
I assumed it was kind of self evident that the “dragon” legends came from old discoveries of dinosaur bones? Dragons are basically depicted as winged crocodiles, which happen to be one of the living animals most closely related to dinosaurs.
Well presumably Mastadon bones might be in better condition.
There’s a picture of alleged dragon bones here. They reside behind an altar in a Greek church. Apparently one Saint Donato defeated this dragon by spitting on it. Interesting martial technique.
ETA: Actually it’s a Venetian church (on the island of Murano). The dragon was supposedly slayed on the Greek island of Cephalonia though.
Awesome! They look pretty fossilized though. I don’t suppose there’s much chance of getting any DNA out of them?