Murray Rothbard believed fractional reserve banking is fraud. Without going into much reasoning and detail, it appears Chazal disagree. I have never seen a breath of condemnation of honest bankers in Gemara.
A banker is called a “Shulchani”. Or, in Greek, טרפסיטים, Bamidbar Rabbah 4:8.
Unless bankers are a state cartel or guaranteed by government “insurance”, what could be or go wrong?