The banking system can expand an initial deposit of $100 into a maximum of $1,000 at a 10% reserve ratio when subsequent loans are re-deposited. ($100+$90+81+$72.90+...=$1,000). This all gets counted as M1 money.
The claims others have on you must be balanced by claims you have on others, otherwise you're defrauding your depositors; and if you want to accept money from the public, your words can't be taken at face value but need to be verified (and publicly supported) by trusted, independent external auditors.