~snip~
This is why we should never plan to keep our coin on exchanges because this might make us lose some good amount of money if the exchange crash. The people that have big funds in FTX cannot still access there funds till today because of the mismanagement of funds if customers by the team. Exchanges are using our money to make themselves richer when we swap our coins and trade on the platform.
If many of these exchanges crash, many investors are going to lose there money because many people are not still ready to remove there funds from exchanges or reduce the amount of money they have there maybe in case they want to swap or trade on the platform. Bitcoin will always fall and rise so we need to be ready for anything the market want to do.
Yes, you should always keep your bitcoin in your own wallet.
Exchanges should be used only to exchange bitcoin, as the name implies. There's nothing good about storing your bitcoin at their wallets. Ideally you should setup an automatic transfer after a threshold is reached, and always keep your money off exchanges.