In wealthy countries, any additional prosperity cannot be the factor that can make people more satisfied and happier. I partly agree with this idea, as this can make people satisfied more, and in some cases it cannot do so.
On the one hand, being richer and having better facilities can make people satisfied more. In order to have a happy and satisfied life, we need to have food, fresh water, and accommodation. If a country is rich enough, it is really easy for this country to meet the needs of its citizens.
When countries have enough money, these countries can have better roads, transportation, and education. If the education and transportation are good, people will have nothing to complain about, which can create a chance for people living a happy life.
On the other hand, in some situations, being wealthy cannot be the key to becoming satisfied. For instance, England is one of the wealthiest countries. But still, I cannot say that people are having satisfying lives out there. The reason is that there are other problems that can make people sad. For example, crime rates are higher in England than they are in other countries. In other words, we need peace in the first place to be satisfied. As I mentioned above, we need three basic needs (fresh water, adequate food, and good accommodation). If people have access to have those needs, people can be satisfied whether their country is rich or not.
In conclusion, wealthy countries indeed can have a happy and satisfying life. However, it is not always the wealth that can make people happy and satisfied; it is actually the peace and basic needs.