You are right but the true essence of crypto wont really fit out yet entrusting your funds will be most likely with fiat banks.Nothing is really safe but
holding your funds with your own wallet do really gives out some convenience compared to other.
Your own wallet can be accessed by hackers using many different tecnique or strategy by hackers. Examples like clipboard hijacking in which hackers are able to change the information you copy like wallet address and when you paste the wallet address is not the same as you copy and they able to take you cryptos when someone got hijacked and trying to send btc to someone.
So security of your device is that much weak to copy the clipboard of you.But copy clipboard is not like just you mentioned,while you are login to not trusted site they may copy what you have on clipboard and can steal your private keys if you have on it and access you wallets later.