"Why do people have a problem with prosperity teachings?"
For the simplest reason in the world -
THEY DON'T WORK!!!!
There's essentially not a penny's worth of difference in the actual "Prosperity" of a "Normal Christian", and one who's sitting under "Prosperity teaching".
In fact statistically, the MOST economically disadvantaged folks in Christendom are MOST LIKELY to belong to the "Full Gospel" genres - Pentecostal/Charismatic groups - which, of course include "Word of Faith", and "Prosperity" sub categories.
The TEACHERS of prosperity (The Hollywood crowd) - obviously experience "Prosperity".
But the "Rank and file"???? Nothing.
And since folks are becoming more AWARE that "Prosperity" doesn't work - there's a growing skepticism about it, as there SHOULD be.
There IS, of course, a BIBLICAL "Prosperity" - which is always for the purpose of "Blessing others", and not for selfish consumption.