Residential customers don’t use anything close to maximum bandwidth regularly.

It gets better as you with faster connections and more users. At 100Mbps you can roughly do 20:1 over subscription, bump that to 1Gbps and 50:1 generally works fine. StarLink is aiming for roughly 50-100Mbps connections so this likely represents around 20,000 to 40,000 customers per 100Gbps link.

“SpaceX - Starlink (AS14593) has added 2x100G bringing their capacity to a total of 2x2x100G. They are connected to the route servers.” In other words they hit 40,000 to 80,000 customers and are preparing for another 40,000 to 80,000.