You are right. So he played by the rules and got $31M. The point is, the "good" exchanges with worth of billions $ weren't not hacked yet. So that puts a lot of trust in them.

You basically have the same scam in clasical finance. There are a lot of examples, even one that caused a financial crisis. So let's say it can be a good thing that "bad code" or "bad asset management" is discovered early.