No, it's not wrong!!!.. So what should he teach, that Christians will be poor?
.. Doesn't God want us to Prosper?.. 3John:2, 2Cor8:9..Take a look at most children of God in the bible, they were all richly blessed!.. Abraham, Isaac, Jacob, Joseph, David, Solomon..etc.. Christians do not neccessarily have to be rich, but there is nothing wrong in teaching about prosperity. It's just not important, what is important is salvation.
So is it wrong to teach about Prosperity?.. NO!!!!
Is it neccessary?..... NO!!!!!