That’s a big part of it as well. I’ve seen that in the corporate environment. In the name of cutting costs, they’ll refuse to increase bandwidth until the infrastructure is under a constant crippling load before adding more capacity. As long as it works for most people most of the time, they consider it fine and not in need of upgrades.
Had that happen at work with our VPN before lockdown. People had been requesting more VPN access for years. Folks in charge said no that it was too costly and we didn’t need it. Then the pandemic struck and everyone had to work from home… It wasn’t pretty. They’ve added a bunch of capacity now though. But it took a massive failure to make it happen.
ISPs do this all the time as well. A new subdivision pops up in a city, connectivity requirements go up significnatly, but they jack into the trunk that was feeding already a bunch of nearby customers without adding more bandwidth to it congesting everyone’s traffic.