exchange security or kyc will be exchange's policy. They need customer personal data in order to record money flow if something wrong happen. For example if exchanges hacked ,they could track this fund run to which people and block address to avoid massive dumping . Personally i am comfort with this policy. It give me certainity and comfortable. Unfortunately many traders didn't understand about it.
For you to make sure that your funds is safe or your asset, make sure you only trade on a real exchanges and top exchanges like binance,hitbtc,livecoin,bibox and so many more, you may see it in coinmarketcap list of top 10 exchanges. It is good to know that these exchanges having a great security that it is too hard for the hacker to control, it makes our worries gone and our assets safe. But you need also to strenghten your password security.
After buying bitcoin or altcoin and you want to keep save for long term keep hold your assets in offline nano ledger wallet, I think many benefit if you keep holding your assets in nano ledger wallet because very safety than you keep hold with exchange market account, some time exchange can hacked like upbit and you have waiting more time for withdrawing your balance.