I've kept some of my coins on Binance for like three years and I haven't lost any. However, I knew what I was getting myself into by doing so, they could've locked my account for any reason and could've ended up losing my assets. I think some of us are addicted to convenience even we know the risk. Those who stick to " not your keys not your coins " rule are usually people who've had a bad experience and have lost a lot of money by trusting a third party.
I can understand why people like the convenience however this to me only makes sense for those which trade the markets every single day as even if the fees for withdrawing your money are small they add up and soon they could become and important cost you need to pay, but for those which are not traders and are using their exchange wallet as their main wallet then this is a huge mistake as they are giving up their privacy and the ownership of their coins for no benefits at all.