It's pretty standard for banks to "go down" outside the hours of 9am-5pm. Nearly everything meaningful that a bank does is processed in batch, often with days-long delays.

Operationally, Facebook is a vastly harder problem.

Multi-hour outages are already relatively common and getting more frequent by the year for banks. About 10 days ago there was a massive Bank of America outage.

You certainly don't use banks often, because their systems being offline for several hours is a relative common event.