The difference with boas is that they take longer to mature, so people with the get-rich-quick mentality don't want to wait that long for their critters to grow up. Plus they require more expensive caging, you don't keep seven foot or larger breeding females in a rack of 41-qt tubs.
Heck I also have 1.2 savu pythons I plan on breeding when they mature, but females aren't ready until they're 5-6 years old. I mentioned that to a friend who also keeps BP's and he was like... so how the heck do you make money if you have to wait that long for a female to grow up?