Prosperity in the Old Testament was a belief that if you were right with God and worked hard, you would prosper in the sense that you would have abundant harvests, large herds, and numerous children. This is hardly the view of prosperity held up by the purveyors of prosperity gospel today. Further, the Old Testament writers are wonderful. They follow the time honored Jewish tradition of argument. Where Psalms, Proverbs, Ruth, etc. may assert this position, Job, Ecclesiasties, Amos, Micah, etc. argue against this position. Plenty of wicked folks were prospering. In Job the writer goes so far as to show the main character, a very faithful follower of God, losing everything. Way back then, the people of Israel were doubting the accuracy of "prosperity gospel."
Along comes Jesus, who reverses the prosperity gospel agenda. As seen in the beatitudes (blessed are the ...), Jesus lifts up the poor rather than blaming them for any lack of piety. Jesus even speaks to a redistribution of wealth (see Zacchaeus, the tax collector wringing his local community dry for his own profits and his turn around as an example). The rich young man who seeks Jesus' advice is not automatically considered pious by his possessions. Later, James writes a powerful and prophetic slam against wealthy folks who oppress their workers.
In the end, prosperity gospel as preached and practiced by some today is a swing back to a very Old Testament position. This is a position that overlooks the counter arguments of the Old Testament and all of the reasoning against that position that is found in the New Testament. Far worse is an attitude "prosperity gospel" can create. Adherents are likely to assume that those who are struggling simply aren't right with God and therefore there is no need to help them, no need to show compassion, no need to do anything other than tell them to get themselves right with God. This is wrong. This is heartless. This is cruel. This is not gospel and counter to everything our God of love stands for. Just wanted to take a moment to present a counter position.
Have a blessed day.