There could be several reasons for not buying authentic Van Cleef & Arpels jewelry.

Firstly, the price of authentic Van Cleef & Arpels jewelry is very high, and may not be affordable for everyone. It is well known that Van Cleef & Arpels is a luxury brand, and their products are priced accordingly. Therefore, some customers may choose to buy cheaper alternatives, such as replicas or knockoffs, in order to save money.
Secondly, some people may be wary of buying authentic Van Cleef & Arpels jewelry due to concerns about the authenticity of the product. There are many counterfeit or fake Van Cleef & Arpels products on the market, which can be difficult to distinguish from the real thing. Therefore, some customers may choose to avoid buying authentic Van Cleef & Arpels jewelry altogether, in order to avoid the risk of buying a fake or counterfeit product.
Lastly, some customers may simply not be interested in buying authentic Van Cleef & Arpels jewelry. Everyone has different tastes and preferences when it comes to jewelry, and some people may prefer to buy from other brands or designers. Additionally, some people may not be interested in jewelry at all, and may choose to spend their money on other things instead.
Overall, while there are many reasons why someone might choose not to buy authentic Van Cleef & Arpels jewelry, it is important to remember that everyone has different preferences and financial situations. Ultimately, it is up to each individual to decide whether or not to invest in luxury jewelry, and whether or not buying authentic Van Cleef & Arpels jewelry is the right decision for them.