The truth is if you had one Bitcoin in FTX, that was worth 20k. You might have bought for more or less than that. Now it's worth 60k. You didn't get the 20k back immediately (in which case you could have repurchased the Bitcoin immediately and not lose anything).
- If you bought Bitcoin above 20k, you lost money, whereas you wouldn't have otherwise. - If you would have kept your Bitcoin, you would have 60k now. You didn't get a choice in the matter.
The problem if of course "what is money" — the thing you owned was a Bitcoin, and now you're getting back its value from back then in dollar terms. This value changed meanwhile, shocking! But quite clearly, most people would have had more money now if that hadn't happened.
So while it's possible that some people would have sold lower than 24k (it didn't stay that low very long), most people wouldn't have, and so they lost money, in the commonly accepted undertanding.
Imagine the government seized your house 10 years ago, then paid you back today its price from 10 years ago +20%. Did you not lose money?