The thing to keep in mind is that true genius is just inimitable.

Probably none. Marie Curie’s accomplishments were not stolen by her husband. And it’s not possible, really, for academics to steal work of this quality. Suppose they were to submit it under their own name? There would inevitably be some imperfections in the original submission, and revision would be required. And the thief would be stymied.

Plus, the thief or thieves would have a hard time explaining what led them to the result. They would not be able to explain their work at conferences.

When a strong mathematician steals the work of a lesser light, something that is rare but not entirely unheard of, they may not have had the insight or done the work, but they at least can understand it once they’ve seen the key clue. At the top, it’s different.

We can also reason by analogy. What happened to Ramanujan? It would have been the simplest thing to just not acknowledge receipt of the letter, and set to work deriving the conclusions on one’s own. Who would have known? Ramanujan, an obscure nobody in India, would have had no chance to vindicate his claim of first discovery. Assuming, of course, that a stellar mathematician like Hardy would have been up to unpacking Ramanujan’s discoveries. (Which he wasn’t. Genius being inimitable.)

What happened? Hardy invited him to Britain and lavished praise and credit on him. The war, (WW1) unfortunately, meant that praise and credit could not feed the body, and Ramanujan contracted TB, couldn’t fight it off, and eventually died of the disease. But he wasn’t robbed.