> in the game industry there is no guaranteed reward at the end of the development cycle
The same is true for any product industry. There are things you can do (customer development, short iterations that involve your potential customers, etc) to increase the chances, but if you're not doing work for clients directly, then there is no guarantee.
Note that the "doing work for clients directly" exists in game development too, there are many freelance or services companies that do work for other companies, and from what I hear about the game industry, these have much more guaranteed pay, just like outside of games. Its the "build the product, when its done, hope someone buys it" type of work that has no guarantees, but that is in no way unique to game development.
The difference is, most other industries don't have such crazy crunch times...