Our deposits are liabilities for the bank (the bank needs the infra to secure the money, make it available everywhere at every ATM, bank tellers and so on). Banks invest the money (and give loans) to both pay for these costs and also make a small return on top.

It is possible to have a bank that just stores the money without touching it, but this bank would charge us for the costs of doing so, and it won’t be free, and it won’t be popular vs free options (which once every 10-20 years blow up).