If you plan to sell or exchange your coins over the next few years, experience shows that storing coins in a cryptocurrency exchange account is no different from storing them in a wallet. And in many ways it's even more convenient.
You didn't get the point, the reason why you shouldn't leave your coins in exchanges because you can't know the exchanges is still operated or not in the future. If you have leave your coins on an exchanges which never got hacked until now, you're lucky since every year there's always an hack incident. I would rather spend some satoshis and times to secured my coins fully 100% on my wallet rather than leave them on exchanges to save some fees.
you can gain interest on reliable defi platform if you make research well enough.
That's a same case like leaving your coins to centralized party.
The worst place to keep your coin is on exchange wallet address, you might be enjoying interest but just know that your funds is not safe there incase if anything happens to the exchange then their is no assurance that you are getting back your funds, we have heard about different exchange hack that have been happening and people are losing their money which I believe there are still more hack which will happen and you leaving coin on an exchange then your coin is definitely at risk because you can lose them.