As said wallets from exchanges and untrusted platforms is always risky. We don't know when they'll wind up and run. When it comes to bitcoin and other cryptocurrencies, we should not get into it just after someone's words. We should put our efforts and understand before getting into it. This way you can have the basic understanding which is a must to keep everything secure and in an organised way.

Actually wallets can also be hacked if someone uses a software wallet from an untrusted source because now there are many software wallets that can be used to store Bitcoins. But not all of them can be suitable for use if the source is not trusted or they are born from an unknown source, so this has not only happened through exchanges but has also happened through software wallets used by users who may not know that the wallet is not good.

It is very much advisable not to be in a rush to invite a friend to what you don't really understand. You needed to spend more years here and in bitcoin and atleast understand how things work yourself before you invite anyone. It won't be a good experience when your close friend lose money because of you.


You are wrong
Bitcoin security system which is PoW is for the security of the bitcoin network which doesn’t cover an ordinary investor. There are many cases of wallet hacking, and it is easy when to accomplish when your device is compromised.