Because doing it one time, or 10 times, or 1,000 times doesn't change anything about how it works. If everybody pays all their debts, it all adds back up to $1,000,000 in cash (plus interest for the bank(s)).
No it doesn't. In my example the bank loaned out $850k to the first small business and $723k to the second. That's $1,573,000. The bank started with $1million.
It absolutely matters how many times the dollars come back to the bank because that is the pathway that lets the bank loan the same original dollar out multiple times.
I think you’re forgetting the bit where the business that took the $850,000 loan is left with $850,000 debt and $0 balance after they spend all of it. Every time it passes through the system the amount recirculated simply decreases by the reserve %. It all still adds up to the original amount (plus interest).
In your example though, the bank has a different problem of offering unsecured loans, which could lead to some losses for them.