Collectors, idiots, and some shooters.
Film is actually increasing in use, even Kodak says their film division is making money these days.
But when you think of it, all those professional photo studios that have gone to digital, and rightly so for commercial work, have dumped their LF cameras over the past few years, so you would think that there are 10 LF cameras out there for every one wanting one.
But if you go over there on
http://www.largeformatphotography.info/forum you will see all kinds of people bragging about their 18 cameras and 64 lenses. They think they are photographers, but they are really collectors. Not that there is anything wrong with that, I have 6 folding roll film cameras myself, but if these guys each buy 12 cameras there is a shortage for the rest of us.
I have been happy with one lens for my Crown Graphic, and would be more than happy with 3 for my recently acquired monorail. However, others are not happying unless they have 10-12 210mm lenses in their collection. So they are driving the prices of LF lenses up.
Then there are those guys new to LF who are buying stuff, having no idea what it is actually worth, and paying 2-3 times as much as they were going for. Of course that helps drive prices up too.
Next you have those eBay opportunists. You know the guys with a BIN pice of 5-10x the going price. Some of the buyers in the previous paragraph see those prices and think that is what things are worth.
And finally, with all the losses people have had in the stock and futures markets they are buying stuff they think will increase in collectors value instead of their usual investments. As they do not really know what they are doing, they are going to lose their butts again, but they have more money than sense, so there is nothing new about that.
However, there are still bargains out there. Craigs list is a good place to look if you are in a big city. On eBay you still can occasionally find an honest seller who is not lying about the conditions of what they are selling (I had 9 items not as described in a row this past winter). However, those sources require a lot of patience to get a good deal from. I have found quite often that I get better deals from dealers websites than from Craigs or eBay.
Color film has shot up quite a bit in the past 2-3 years, some B&W is still reasonable, especially from the smaller manufactures. But in the film photography world things are not going to go back to the low prices we saw 3, 4, 5 years ago.