Start by building a business that isn't differentiated by how many 9s you have. Something customers want so badly that a few hours of inconvenient downtime doesn't move the needle at all.
In this situation, blowing up your system complexity to maybe get another 9 makes no sense. Then the revenue change is pretty irrelevant for modest downtime.
People under estimate single server uptime. If availability is really that important, buy a hot backup. Put it in another region. Done.