I've been asked this several times, so I'll explain it here.
Transfers between users on the same platform are usually recorded only on the platform's ledger, not on-chain, so they often arrive quickly and incur no network fee.
Self-custody means you have both the control and the responsibility: there's no platform-level risk, but there's also no “password recovery.” A mistake often can't be undone.
The $BNB in your Binance account is held in custody by the platform. Once you transfer it to a self-custody wallet, you'll be responsible for safeguarding the private key yourself.
If you learned something, comment “1.” If you're still unsure, leave a comment and ask more questions.

#BNB