What you say is possible, although we know that Interpol issued a warrant for him very soon after the collapse of his project and at the time when the news that he was in Serbia appeared, his original passport should have already been canceled and I doubt that he used it. However, it turned out that even those who have a lot of money do not have to be intelligent, because people of that profile (internationally wanted) hire a private plane/ship or whatever and disappear without having any problems with border controls.

Rich and spoiled characters like De Kwon or Bankman probably consider all this to be a game with high stakes, and time will tell if the game was successful or if they will become roommates in prison.