Many comments seem to cast doubt on the marshmellow test based on the article. I honestly don’t understand how the contents of the article could lead to such co

Many comments seem to cast doubt on the marshmellow test based on the article. I honestly don’t understand how the contents of the article could lead to such conclusion. Aren’t the economic status of the family and the result of the test both correlated with the future economic status, and no causal relationship is suggested?