In a story that will sound familiar to anybody who followed the collapse of Canadian crypto exchange Quadriga, two brothers who ran a South African crypto exchange have absconded with Bitcoin worth $3.6 billion stolen from their clients, demonstrating once again the one glaring security weakness: While hackers are believed to have brought down Mt. Gox, disillusioned insiders with the right kind of access can easily run off with a life-changing amount of wealth. And in many cases, clients who trusted the exchange to safeguard their assets will be left holding the bag.

Africrypt Chief Operating Officer Ameer Cajee, the...