The decent restaurant is a good example: For the price of a 9000$ diamond ring, you can eat a fancy dinner at a 300$ restaurant every year for the next 30 years

The decent restaurant is a good example: For the price of a 9000$ diamond ring, you can eat a fancy dinner at a 300$ restaurant every year for the next 30 years of your marriage. And the money is probably spent much better that way. You'll build up memories of shared experiences.