Pro Wrestling has its roots in old carnival shows or "carnies." Carnival shows used to have people legitimately grapple, and promoters started to realize the drama these bouts would draw from an audience. This motivated the idea to start fixing the fights to deliberately make them more dramatic so that people would want more. From this point it became more of a violent performance and has since evolved into modern professional wrestling.
The short answer as to why? It makes money. Another reason was the actual pro wrestling would have hour long matches. It was real wreslting (college or olympic style). Matches took too long and had little or no drama. Fans lost interest. So, promoters started booking shorter matches with scripted finishes. This drew the fans back to the matches. Eventually, the public found out that the matches were fixed when the guy responsible for sending the results to the newspapers sent in the next nights results. He was drunk. (This was detailed on the A&E special about wrestling in the 90s.) However, I totally agree with the short answer. It makes money when run well. Wrestling had a boom, in my opinion, because you knew that you were getting three hours of entertainment when you bought a pay-per-view. Boxing could have 30 second fights.
Pro Wrestling America was created in 1985.
Impact Pro Wrestling was created in 2001.
All Pro Wrestling was created in 1991.
Pro Wrestling Illustrated was created in 1979.
One Pro Wrestling was created in 2005.
Tokyo Pro Wrestling was created in 1966.
Xtreme Pro Wrestling was created in 1999.
Fire Pro Wrestling was created in 1989.
Metro Pro Wrestling was created in 2010.
Pro Wrestling Illustrated awards was created in 1972.
Pro Wrestling Report was created on 1998-03-18.
Windy City Pro Wrestling was created in 1988.