Overall, the authors confirm that there is indeed a significant negative relationship between materialism and well-being, such that individuals who are more materialistic are less happy/satisfied with their life. In fact, this negative relationship holds over all categories of well-being, but is especially strong for physical health and mental health outcomes (this means that people with materialistic goals are more likely to have negative health symptoms, are more likely to engage in risky health behaviors, and are more likely to consume compulsively).
Interestingly, the authors find that the relationship between materialism and well-being is not affected by demographic factors such as education or income, but is affected by others, such as gender, age, and profession. The relationship is stronger for women than men (meaning there is a larger effect of materialism on well-being for women), as well as for older people (compared to younger people). Another interesting finding: there is a weaker effect of materialism on well-being for people working in materialistically oriented professions such as economics, marketing, and business. This is believed to be true because these professions offer a match between the values of the individual and the priorities of the profession, which leads to greater validation, an easier time conforming, and less conflict between internal and external goals. Despite these changes in the relationship by some characteristics, it's more interesting that the negative relationship broadly holds across most demographic, economic, and cultural factors. Thus, everyone is made worse off by being materialistic or having materialistic goals. It's important to note that since this is a meta-analysis, the authors are not evaluating whether some of these cultural or societal factors can affect how materialistic an individual is, they are only saying that controlling for a level of materialism, its effect on well-being holds across these different demographic characteristics.
Ultimately, the meta-analysis confirms that any way you cut it, being materialistic hurts you. And, yes, some factors can reduce the level of that hurt, but nothing the authors looked at found a positive or even neutral relationship between materialism and well-being (i.e., under no circumstances did being materialistic lead to more happiness). Now, if only they had a recommendation on how to change how materialistic a person is.