Well the answer is that many, many that do their research and no just follow hype or trends would have know this would happen or better still anticipated that anything is possible in Crypto-currency and you are meant to also think about the worse possible outcome.

SBF isn't an upright man and if you had looked at his past and that's before the FTX case you would know he had some history of ingenuity. There are always hints and clue you are meant to fix up that can help in carrying out the right decision in crypto-currency but to find them you have to do your research.

Also the cases you wrote is not in any relation with Bitcoin, because some people that had issues with FTX are bitcoiners but rather your approach to crypto-currency is more important than what you are holding .