Actually, in the DCU, David Copperfield probably has actual magic powers. Think about it: David Copperfield grows up, and he's like, "I'm going to be a stage magician." But like you said, in the DCU, stage magician, like you said, means Zatara. A genie in human form.
So the path from neophyte to prominent entertainment leads through the shadowy zones, full of dark magic and ancient enemies as you fight to possess objects of power in the ruins of ancient [insert vanished culture] temples.
And once he gets there, he probably wonders why he's a guest spotting on Letterman when he could be fighting Starro. Then he realizes the Justice League does not receive a salary, let alone Claudia Schiffer.