Why Bandwidth is more important compare to Disk space?

Disk space refers to the amount of usable space on a storage device. The amount of space is measured in bytes.
Bandwidth is the maximum amount of data that can move from one point to another over a given amount of time.
disc space can be handled easily but bandwidth can only be provided well by a good hosting service provider.
many service providers can provide disc spaces easily but bandwidth is a very important and crucial topic that can only be provided by very few providers.