FTX was a brokerage though, not a bank. While banks may be inherently allowed to accept and lend out customer funds, brokerages seem to be largely forbidden from doing so.[0] SBF appeared to act as if the typical rules of operating a security brokerage didn't apply to FTX 'because crypto.'
[0] https://www.finra.org/rules-guidance/rulebooks/finra-rules/3...