Assuming you cashed out, wouldn't it be something like "that 10% you earned 10 years ago" because if you never cashed out then you're not liable.
My reply would be along the lines of: "Sorry lost it all in MtGox/FTX/Crypto/Vegas/Horses"
My reply would be along the lines of: "Sorry lost it all in MtGox/FTX/Crypto/Vegas/Horses"