You're right, never store your crypto assets on exchanges because even top exchange also have risk of hacked, currently only private wallet like hardware wallet is a best ways to store your crypto assets to prevent hacked, but I think still a lot of investor store their crypto assets on exchange because it's easy to use for daily trading.
Sure may people would have learnt their lessons by now through Binance hack, we have so many people that can rely on these top exchanges too much and before we say anything, they mention top exchanges; meanwhile, these top exchanges are the ones that are more prone to hacking than the smaller ones.
It is when this hackers gets to know about an exchange through the hype that they make it their duty to research then and see their weak points, there is nothing more safer in keeping ones coins than to store our coins in a private wallet with a private key that we have our full control on.