People do simple math 2 rats+food=unlimited income potential. As a former commercial banker, I actually built several business models and ran them up to tens of thousands of rats and most showed some early income potential, then they worked their way up to break even and finally ended in catastrophic financial disaster.
To be perfectly honest, if you can sell rats for about $200.00 each and had a huge market, (we're talking about thousands of rats per year) you can do pretty well for yourself. It could also be done if you inherited a rural farm, had a large family and didn't mind all working for minimum wage.
If rats really were profitable they would be coming from China... If the Chinese can't figure out how to make rats profitable, I can't see that it can be done here...
Our breeder actually breeds expensive fancy snakes, and when he has a few surplus rat pups, he'll part with them to pet rat owners at a premium. Oddly the guy knows his genetics, he loves to breed stuff and he's got skills most likely learned from breeding snakes... He really does breed exceptional rats with wonderful personalities. He says his daughter likes to play with them.
Imagine, a guy that breeds rats like these... and he's not doing it for profit.... it tells you something.
If people would really do their numbers correctly they wouldn't ever get into BYB.