The thought is that God blesses those who please him and that extends to material blessings. I don’t have a problem with that fundamental idea and you can see it in the world surrounding us. However, every person in poverty is not that way because God has not blessed them, just as every person who is materially well off has been blessed by God. Formalizing this into some sort of “Prosperity Gospel” is entirely too worldly and devolves into justification for acquisition of material things for their own sakes, so it’s wrong, even if underpinned by a fundamental truism.