I don’t know Korea’s laws but this would likely be illegal in the US, too. It depends on whether it could be proven that you knew that the stocks were issued in error. And even if it wasn’t a criminal act, the company would be within their rights to recover the mistakenly issued stocks.
This has nothing to do with scared students. This is the result of rhetoric from Trump and Vance about the large Haitian population in Springfield. Violent right-wingers are acting upon their dear leader’s words.