1 Their design doesn't change over time
Rolex watches have a fairly constant design. This prevents them from going out of fashion and as a result their retain their value.
2 They last for long periods of time
Rolex watches were designed to last. The fact that the watches stay functional for decades helps them retain their value. See why Rolex watches are so expensive.
3 High demand
Rolex watches are in a high demand and as a result the used ones get sold easily. This is another reason why they retain their value.
4 Prices of watches increase
The prices of newly manufactured Rolex watches have been on the rise. The fact that the price increases while the design remains almost the same helps old watches retain their value and even increase in prices in some cases.
5 The addition of precious metals
The fact that some watches include precious metals ,such as Gold, helps them retain their value.
6 They don't become obselete
Mechanical watches don't become obsolete as a result of technology changes unlike mobile phones for example. This helps them retain the value more than most gadgets.
7 They created the proper brand image
Rolex created the proper brand image and convinced people that they retain value. As a result people started selling used ones for good prices. See why branding is important.
8 Swiss franc appreciation
Some suggest that the rise of the Swiss franc against the USD in the past 30 years was one of the reasons Swiss watches kept increasing in value.
9 Scarcity of some models
The Scarcity of some Rolex models and of Rolex watches in general makes them more likely to retain their vale. Only 1 million Rolex watches are produced every year.
10 Very high demand on some models
Generally the models that cost between 4000$ and 9000$ are in high demand. This helps them retain the most value.