While it was possible that others had purchased the Infinity Mu Jins, there definitely would not be many.
Simply put, the Infinity Mu Jins were external objects, and using them came at a cost. Angel Yan had not purchased them for their abilities, but for their nearly infinite energy supply.
Besides that, Angel Civilization also wanted to study the internal structure of the Infinity Mu Jins.
Ninth Son of Great Qin: "The Reality Stone's power to twist illusion and reality truly holds unimaginable temptation for some people."
Ninth Son of Great Qin: "As long as one can afford the price, everything one imagines can be made real."
Ninth Son of Great Qin: "But that price is not something just anyone can bear."
Ying Zinian had once entertained thoughts about the Reality Stone as well.
It had been a fantasy from before he transmigrated, when he was still an ordinary person. He had thought that if he possessed the Reality Stone, he could materialize things from anime and novels into reality.
Such as Devil Fruits from the Pirate World, Noble Phantasms from the Fate World, Kamen Rider Drivers, and the like.
But anyone who understood the Reality Stone a little better would know that was impossible.
The price of using the Reality Stone was far from small. Otherwise, Thanos would not have needed to run back and forth with the Avengers Alliance; he could have simply used the Reality Stone to bring the other Infinity Mu Jins before him.
He could even have directly created more Infinity Mu Jins.
Why did Thanos not do that?
Because the cost was too great. Even he could not afford it.
Ninth Son of Great Qin: "Moreover, items materialized by the Reality Stone are like rootless water or castles in the air. Such objects surely