My opinion is that buying a desirable vintage watch is more of a trade : cash exchanged for the watch.So I guess you wouldent spend the equivalent of 4 1/2 months income on a watch you really really like ? sometimes and only sometimes your heart has got to rule your brain, you may not agree but as you get older you may see the sense in it and from what I can make out your a long time bloody dead so we need to live a little while we are able.
The watch has pretty much a world-wide established value so the watch can be re-exchanged for cash at any time. Owning the watch does not incur costs like depreciation, property tax, or maintenance fees. Most likely the cash will be worth less next year due to depreciation
Rolex has used this principle for years.
Personally I'd love to buy into such a nice 6159. Odds are it will be valued even higher next year.