I see you understood him correctly.

I agree with you that storing bitcoin in accounts on centralized exchanges is very dangerous practice. It is not recommended and many warnings about it everywhere. With Bitcoin, you can have private keys that help you control your bitcoins, and it's free to own so it's hilarious that people give up freedom and full control from non custodial wallets by using centralized exchanges.

Reminder: do not keep your money in online accounts.
Not your keys, not your coins.
47 crypto exchange shutdown by Germany
Recent events should make everyone withdraw all their coins to their own wallets: Part 1
Recent events should make you withdraw all your coins to your own wallet: Part 2
Recent events should make you withdraw all your coins to your own wallet: Part 3
Get your coins out of custodial wallets now: Part 4