My two uncles were professional weekend wrestlers (part time wrestlers who work as a sideline) who went under the name of the Cadot Brothers and this is what they told me. It really has a lot to do with the wrestling promotion and the wrestlers themselves. A lot of wrestlers are very competstive and don't like putting their opponents over, and even refuse to do it. Some promotions have two pay windows, one for a win and a lesser one for a loss.

So basically while there is a lot of fakery going on, not all of it is. Added to that some wrestlers do not like each other for real and they go at it in the ring.