But they need exchanges to get real money to flow in and out of cryptocurrency easily. Without it, cryptocurrency by itself would likely be worth far less than it is today.
Yes that's true, but no need to hold your crypto there as a permanent storage. Once your fiat is exchanged to crypto, immediately transfer the crypto to your private wallet.
As opposed to the bank's ...? Or your other account's ..., what exactly, passwords? Phising is everywhere. How many times have you heard the elderly have their money stolen, both online and in real life? It happened to my grandma. The mailman is bringing her own pension as cash, and guess what, he has scammed my grandma for years! The food delivery guy who has been delivering lunch for my grandma, guess what he did? He scammed my grandma out of her money! We are talking about cash, right now, and no phising involved, just good old "lying".
Hence why cryptocurrency would never replace regular banks for regular people. The situation with scams and thefts has only gotten worse. Not your keys, not your coin.