A few paid survey sites do pay relatively well in cash. However, many sites hype hypothetical, best-case scenarios that can't possibly apply to each and every consumer for each and every hour of participation. In the real world, the likelihood that you'll often earn the higher of the hyped amounts is slim. Most online paid surveys simply don't pay much, and you must be invited to complete them. To be invited, you must fit targeted demographics. That alone limits your earnings right off the bat, as you can't possibly fit every demographic.
Paid survey site companies invest billions of dollars into marketing research online. They always want to find out more intricate details of a consumer's relationship with their product. Whether it's a new television show or just an existing product line, companies like Disney, Samsung, and Sony go to great lengths to find out their ideal audiences.