is investing in luxury watches a good investment for singaporeans?

Only if you pick the right pieces.

Additionally, you will be looking out not just for authenticity and craftsmenship, but also demand. Ultimately, if you are looking for watches as an investment, you would be looking for a coveted item that can command high prices from buyers later in the future.

Advantages:

1. #HIGHSESlife - but seriously though, some people do feel compelled to dress the part especially when doing business. If I wore a watch though, I would just wear one that serves its function, and not wear my investment pieces out.
2. Family heirloom. Remember the iconic Patek Philippe slogan: 'You never actually own a Patek Philippe. You merely look after it for the next generation.' A Patek watch does not merely tell time. It’s an heirloom that transfers values across generations.” Ah, the allure of marketing like that.
3. Diversifying your portfolio. It is important that you conside the demand of it though. So it's important that it's piece that you will enjoy, even if the demand for it goes down.

Yes. It's an exotic investment you need to learn over time.

See here to start:
https://blog.seedly.sg/luxury-watches-investment/