if we choose the bank just as we keep our money safe, even the money we save in the bank is diminishing due to the cost of storage. whereas if we want to put our money in bitcoin will get income, because need to know that this bitcoin can go up and down.
Don't forget that banks are lending our money to other people and earn on it. We are given a small amount of their profit but we all know how much money they all earn. Storing money in banks is as uncertain as using Bitcoin. Bitcoin value changes almost every second. Banks could collapse basically anytime and disappear with our money.