Storing your coins in an exchange is one thing that should be discouraged, because it's not a very good practice storing your coins on an exchange, when you store your coins on an exchange the truth is that you don't have full control over your coins. The exchange can short down or even lock your funds all in the name of KYC verification. Storing your coins on a cold wallet should be encouraged over exchanges.
In a much as I agree with everything you’ve said about centralised exchanges not being safe to keep our bitcoin because of the third party involved, and that if by any chance anything goes wrong, we might lose our coin since we are not in total control of our wallet security, but we can not dispute the fact that it has made our bitcoin transaction way easier than the non non centralised exchanges.
Sending your bitcoin to a wrong address is one mistake that happens sometimes. But this can be avoided through double checking of the wallet address. Because when you send your Bitcoin to the wrong address it will be difficult for you to get your Bitcoin back.
I have always said it that double checking address before confirming transactions cannot be over emphasised you will not realize how little mistake can make you lose your coin and you possibly will not be able to get them back. I had made a post here earlier about my friend who copied an address from his history and did a transaction which he was unable to trace the owner of the address and that was how he lost those coin.all this little mistake are avoidable if you are careful and patient enough to do the necessary checks.