Circa 2000 my wife and I were planning to get into farming and would up visiting quite a few Llama and Alpaca farms that were frequently run by very rich retirees from corporate America. We wound up keeping horses which are a much better business because people really do want to ride horses.
Up to 150lbs of muscle, claw, and beak, and they can stand over 6ft tall.
Emus are so weirdly neurotic and aggressive, I hate being around them. If an Ostrich is even more unpredictable than an Emu it's hard to imagine farming them would even be possible.
If I had a bit more land I'd quite like to have some Emu. I like them and my mother is scared of them so I see only positives.
There's one spot where there's a bridge over what's effectively a ditch with a small creek running through it. A few emu followed us around the park, but several of them camped out on the far side of the bridge.
When I drove into the bridge, they all moved to the middle of it and boxed the car in. They wouldn't let us pass until most of them got a handful or so of food.
It was quite surreal, and I don't know that I'd enjoy trying to run a farm of large birds like that.
Emu on the other hand are small and relatively docile but still pretty dangerous very smart and can jump very high, so fencing is no joke.
I just dont see any upside to raising these giant birds