there is so much money floating around the world, it's obscene. Someone starts a fad, and pretty soon everyone jumps in feet first. It's not just watches, it's vintage cars, firearms, etc. Right now vintage watches especially the ones that get "talked up" a lot are red hot. Who knows how long or high the prices will go? the vintage market has been pretty strong for a while now. But like all markets, no matter how popular now, are cyclical. I remember a good many years back when Ferrari's were red hot as well, they were being flipped over and over and everyone was making a profit, and then the Japanese economy tanked, the wealthy Japanese buyers disappeared and suddenly, the Ferrari market dropped precipitously. This has happened in the past in many areas of "collectibles"
Now the upshot of this is the folks who have the funds and "intestinal fortitude" to buck trends, likely are able to pick up some real bargains. The only requirement is that you have the staying power wait out the troughs in cycles and be ready when the price picks up again.
Having said all this, there are certain "things" that are almost immune to the ups and downs of markets. These are the uber rare items that exist in such small numbers in the world, that they create their own market. Cars like the Bugatti Type 57S, the Ferraris from the 1960-70's with authenticated racing pedigrees. There are so few of any of these types of vehicles that to own one, one must first find one for sale and then win the bidding war between all the other well heeled chaps who crave one as well. Same with watches, if you are seeking a special watch of which there are only one or a handful in existence, then you aren't going to get it cheap!!