I understand why some people are preferred to keep their Bitcoins in an exchange wallet and that is for trading, not for holding. But these people know what will happen when an exchange got scammed or whatever, yet they still do it despite the risk because of their trust. It could be a manipulating power that most exchanges injected into the mind of the holders. We know it was wrong but can't change their stances as well as it was their choice. They will change their minds when experiencing losses of their funds from exchanges.
There are very few people that keep their coin on exchange for trading, most of the newbie keep their coins on exchange for holding and some old users also do this. We have many people staking their coins on exchanges which is why exchange have so many coins in their wallets. For traders, using exchange to store their trading capital, they already know that they're risking their coins.
But for individuals thinking exchange are the best place to hold their coins, they're the individual this post is focused on because they would regret choosing exchange over personal wallets when the exchange disappears with their coins or collapse due to hacks.