Why we should patronize investment over savings is that investmet provides more profit than savings. Let's take for example you save money in bank for 3 years, instead of making profit your money would be gradually deducted bit by bit for maintenance, transfer or SMS fee. But in investment like Bitcoin, volatility in Bitcoin will make it to increase, except the volatility is a negative volatile instead of positive volatility.
Why do you think Bitcoin volatility is negative volatility even though Bitcoin can still provide profit opportunities for many people through the investment and trading sectors at this time? And regarding the problem of saving at the bank, actually I also agree with what you say, although maybe not all banks do that because local banks in my country don't cut much monthly costs like you said, except for deposits which can't be zero or In other words, there must be a small remaining balance in the account so that the account doesn't die.