Super oversimplification: FTX was an exchange for Cryptos. No problems there. They also offered a coin of their own. Also, no problems. But then they borrowed

Super oversimplification: FTX was an exchange for Cryptos. No problems there. They also offered a coin of their own. Also, no problems. But then they borrowed a bunch of money against the value of their coin. Fundamentally not good, because it means they now owe customers more money than the customers put in. There was also a trading house that they ran on their own exchange, a competitor who might have triggered the collapse as a prank (Binance), and an over exuberant owner who always seemed to be above this sort of mess.