Isn't it the opposite? He gambled with other people's money and lost big. This is criminal because he won, he kept everything, if he failed, everyone else loses.

We really have no evidence that if he accidentally had a few extra billion he wouldn't have done the right thing and reported his crimes so he could divide the proceeds with people he illegally borrowed money from, though clearly not immediately first he would need to wait for it to come back from loans to his associates where he would have had to augment the bellow market interest rates with money he saved from his childhood allowance.