People lose more money every year stored in their bank accounts and atms as compared to Bitcoins, the only bitcoins that get stolen are because of either carelessness in handing private keys or investing in scams.
i think no people lost his money in bank, it's just lower interest if we compared with bitcoin interest (rising price).
but i think not all people who stored his money at bitcoin get interest, growing his money, some people who buying bitcoin in $700 and hold it, now lose arround 20% of his money.
I agree with your first sentence that earnings from bitcoin is more higher than the interest from banks, I also have my money in bitcoin instead of bank for that reason.
And in your second sentence, it is true that some people have lost their money when they bought them at $700 and after a month saw the price at $600 and $580 etc, but if they hold for more longer they can recover their loss and if they know about trade then they can start trade and can recover their loss sooner.
Yes, some people just get unlucky and worry about losing too much and sell at the wrong time. It because these are just average people that dont know are to even slightly predict when a rise or drop is going to occur.
But at least with bitcoin you will be able to trade and get chances to make money. But banks only sweep money from people. If many people realize about the true nature of banks and true benefits of bitcoin, then banks will disappear for sure.