Ask yourself whether that ISP allowing speeds to languish for more than a decade such that they provide one ~100x increase instead of six or seven generations of ~2x increases has made their total costs lower or higher. The fact that they've been screwing over their customers to save a buck for a long time is not a thing that should inspire sympathy for their expenditures.
What 100x performance difference do you think exists between 30Mbps ADSL and 100Mbps fiber?
The answer is that there exists a box that mounts on a telephone pole. The purpose of the box is to terminate hundreds/thousands of DSL lines and connect them all to the central office with a single fiber optic cable. It allows you to get 30Mbps out of your 30Mbps DSL instead of getting .8Mbps, because the box is close enough to your house to get full speed unlike the central office. It saves the phone company from having to string a new strand of fiber to the premises of every individual customer who lives too far away from the central office for high speeds over twisted pair copper.
The first generation would have been actually installing the boxes, which they apparently never even did. Then you periodically upgrade the boxes to provide faster speeds as the technology improves and/or the cost comes down, e.g. from 1.5Mbps DSL to 3Mbps to 6Mbps to 12Mbps etc.
