Why did Jellal leave Edolas

Why can't earth mages use magic in Edolas without the X-Balls?

Terrestrial mages create and absorb magic from the environment, but Ethernano is rare in Edolas as there is only a limited supply. Think of it this way, gold is no longer found in large chunks these days as it is in movies. Instead, a huge amount of dirt is dug up and turned into gold. It is the same there in Edolas where the excess evolved to create their own magic, but since it was only in a limited amount, people did not learn to absorb or create it so they did not have their own magic to have. Earthland mages, on the other hand, create and consume their own magic. The X-balls made it so that they both need to use magic. The X-balls allowed them to only create their own to use magic. So it's like H2O, but the X-balls just let them use O.

Now Happy and Carla are because they thought they used magic the same way and learned how to use magic that way as they believed they had to absorb magic from the environment but once there was no magic to fall back on they had no idea how to use magic. But once they found out the truth and knew they could use magic without absorbing it. It was mostly psychological as, like Superman, he believed he needed to eat, sleep, and breathe, but when he found out he didn't need to worry anymore, he was sure he would do these things, but that doesn't mean him had to.