On that reasoning any company that is successful and people make profit early on then fails would be a Ponzi. It still looks like Alameda/FTX was initially profitable and then began to make losses which resulted in FTX customers (not investors in Alameda) deposits being loaned/stolen.
An investment fund which is successful early on then is not successful but still pays investors high returns is a Ponzi in my opinion. Many Ponzis in history have been backed by a legitimate business.
https://twitter.com/0xdoug/status/1591161987547168768