No! You should not buy any watches as investments. Watches are not a sound investment. Real estate and mutual funds are. The only sensible reason to buy a watch is because you want to have that watch. This is especially important if it's going to be the only watch you own, or if you're going to wear it almost every day. If there's something on your wrist between 8 and 24 hours a day which makes you happy every time you look at it, that's a very significant thing. Some people like very light watches, so light that you can barely feel it there on your wrist; some people, like me, go completely the other way, and think that heavier is better. The watch you wear should give YOU pleasure. If you got a certain watch because certain other people like it, but it's not the kind that YOU like, well, then, in my opinion, that's just sad. Life's too short to go around trying to impress air-headed fashion-mongers.
(I should certainly hope that it goes without saying that if you don't care about watches at all, the most sensible thing would be not to wear a watch, and to read things like this post because my writing style is gorgeous.)
True, Rolex tends to hold its value better than other brands, but that's only because of the Rolex snobs and the lack of knowledge about other brands. It was not so long ago that, if you asked many people in the US to name luxury watch brands, they'd say, "Rolex..." and then go completely blank. That's beginning to change.
Rolex makes fine watches, there's nothing at all wrong with them, but as the watch-buying public becomes better informed about Patek Philippe, Vacheron Constantin, Audemars Piguet, Jaeger-LeCoultre, A Laenge & Soehne, Omega, Breguet, MB&F, URWERK, Ulysse Nardin, IWC, Chopard, Blancpain, Panerai, Grand Seiko, Piaget, Girard Perregaux and the other high-quality brands which have been there all along, then most likely Rolex watches will no longer be unique in the way they hold their market value over time.
But there's no guarantee about that, either. Watch prices, like the prices of any other luxury goods, have to do above all with the psychology of the people who buy them. People's attitudes about watches, and the inherent quality of those watches, are two separate things.
If you listen to people who say that watches are a good investment, you're likely to hear some irrational statements. Like saying that some watches are "worth what I paid for them," when someone paid $5000 for a watch in 1960 which is worth $5000 today. (If he had spent that $5000 on a house in 1960, depending on its location, he might be able to rent it for 3 months for $5000 today.) Or that "some Rolex watches have risen spectacularly in value over time," ignoring the way that other Rolex watches have not. Not to mention the way that some non-Rolex models have risen spectacularly in value over time.
Still -- to repeat what I said above -- if you really, really want a Rolex, if wearing one makes you happy, and you can afford one -- buy it! Buy it, wear it and let it make you happy! Even if you're surrounded by non-Rolex snobs who wear Pateks or AP's and sneer at your Rolex. Screw them!
There probably are a few people out there who actually can make a living by buying and selling old watches. But they're about as rare as people who can make a good living playing poker. And, unfortunately, like the poker players, the watch dealers often depend on meeting a lot of suckers who think they're good at the game, when they're not.