There is always a danger in latching onto one piece of the gospel at the neglect of the rest, prosperity included.
I think it is also dangerous to automatically assume that because a pastor leads a big church or has seen publishing success that he’s steeped in heresy.
The Bible is full of godly people who were very wealthy, as well as godly people who were destitute. And there were ungodly folks of all different levels of wealth too.
If the point is the gospel is not about the money then it cuts both ways. Not only are poor people not automatically ungodly, but the same applies to the wealthy too.
The key is for believers to search the scriptures for themselves so they can grow in wisdom and discern which leaders are preaching the truth.