All those systems have hours, even days of cumulative downtime per year. Planned and unplanned. The sky does not fall. When you are "three nines" - the other 0.

All those systems have hours, even days of cumulative downtime per year. Planned and unplanned. The sky does not fall. When you are "three nines" - the other 0.1% is the downtime you're tolerating. Power outages of a few minutes to a few hours are utterly normal. Power outages up to a few days due to summer heat and winter storms are part of the rhythm of life, depending on where you live. Facilities that really care about power continuity have batteries and generators (although these aren't perfect either, we once lost a datacenter to a transfer switch maintenance). Broadband is notoriously flaky, to the point that cable technicians' vague arrival windows are a meme. Serious businesses get several independent connections. Even consumers can now fall back to tethering their phones. Credit card authorization gets skipped during downtime. Actual payment settlement occurs in nightly batches, which humans have many hours to shepherd and patch. FedWire keeps banker's hours. Stock markets suspend trading when necessary. Stopping the line is a normal part of the lifecycle of a manufacturing process: when something goes wrong, when there's going to be an upgrade, even for regular scheduled maintenance. Most internet services have some downtime.