I don't see any thing wrong in storing your coins in exchanges. You guys are just making sound like it's a bad thing to do whereas alot of you that are saying such things still keep their coins in Exchanges.
There is everything wrong in storing your coins in a centralized exchange. If you don’t see what is wrong in it, I can point it out for you freely. The most obvious is that you can lose your coins at any moment. Or get restricted access to your assets. It will be so bad that you can’t access it when you need it. Don’t follow those that are making the mistake of keeping the assets in exchange. What do you think would have been the condition of those that lost their assets in Binance exchange, if the exchange didn’t refund them their money? Mind you not all exchanges do refund in hack related cases. Exchange hacks are more common compared to noncustodial wallet hacks. I prefer going with the one that rarely happens.
Both of you are not wrong and not wrong at the same time. The Binance halt after the hack showed me that 60% of people in our local board, maybe in Nigeria, have their coins stored in centralized exchanges, especially Binance. When the cold card wallet was hacked, Nigerians didn't react this way. People were more frightened by the Binance hack.
So, we frown on CEX, but we use it the most, and that is what Xackie is trying to explain. But you are not wrong because CEX is the worst place to have your coin kept. However, people who practise non-custodial wallets are those holding long-term coins.