Such a shame too, but yeah it is overall good for all holders. That type of loss would surely be a tough pill to swallow, eh? All the way from Mt Gox to FTX and everything in between.
The lost of customers' coins in Mt. Gox, FTX or any centralized exchanges aren't entirely lost. The coins can still be accessed and spend, the different is just the person who hold the coins. It's like you get hacked, the coins belong to hacker.
Bitcoin is lost from the circulation supply when no one own the private key or not able to access it anymore.