I'm curious: What is your source for this statistic?
For comparison: There were about 40M non-zero addresses earlier this year. See eg https://news.bitcoin.com/number-of-addresses-holding-btc-tap... [The current number is on Glassnode: https://studio.glassnode.com/metrics?%3Bm=blockchain.UtxoLos...]
FTX is one of the larger exchanges, and FTX bankruptcy headlines say they "may have 1 million creditors". See eg reuters.com/technology/ftx-officials-contact-with-us-regulators-filing-2022-11-15/
Edit: I'm trying to figure out if someone has actual stats or whether the statement is just intuitively guessing. There are so many bitcoin stats out there, it's hard to keep track of it all.