Nobody knew that the company was a walking corpse until it collapsed. The operations of most of these exchanges are secret and their audit statements are fake and fabricated. You cannot dictate how much they own because they can always randomly generate figures without any verifiable proof. The best option will always be to "stay away from centralization"
I wouldn't say "nobody knew". There have been some of us who have been pointing out for years how shady these centralized exchanges are. 18 months before BlockFi collapse
I was making posts warning about how dangerous it is leaving your coins with them. Even their Terms of Service clearly stated that they were taking your money and handing it out to literally anyone who wanted it with absolutely zero collateral or guarantees. Then when these platforms and collapse and people are
shocked that the platforms were doing
exactly what they said they were doing in their Terms of Service.
It's was very obvious to anyone paying attention that the likes of BlockFi, Celsius, Voyager, FTX, and so on, were massive scams. But lots people were blinded by promises of obviously unsustainable rewards and ignored all the warnings. And now it's obvious to anyone paying attention that the likes of Binance and Tether are running fractional reserve scams, but lots of people ignore these warnings out of greed or convenience.