There's actually a huge problem with pet rats in that they're all remarkably inbred. If you don't get your rats from a dedicated professional breeder who's been at it for decades, your pet is likely going to get really sick at the end of their life. Females tend to get catastrophic tumors, and all have extremely delicate respiratory systems. Out of the dozens of rats I've kept, only one died quietly in her sleep of old age. The rest were horrific and gruesome.
Yeah, there'd be a good amount of money in it for whoever can fix rats' genetics.
Funny thing is that this kind of stuff is considered haram by the CCP who are fanatically dedicated to social order.
If a tech billionaire edits an embryo and figures out how to make a human immune to a certain disease or live a better life, that is a win for the rest of us.
And before anyone says "they'd just keep it for themselves" - there has been no medical technology in human history that hasn't become generally available after a couple decades.