Private companies have been put under the regulation gun before. Why should it be any different whether it's an ISP or an electric company? I'm pretty sure phone companies in the US are/were under pricing regulation (as long as they use POTS lines, thanks to loopholes). This is what happens with virtual monopolies -- and, in some regions, actual monopolies.
Of course, it shouldn't have to be like this. There should be competition so consumers have somewhere to go when they don't like one carrier's policies. But, they've crafted themselves regional monopolies. Until local-loop unbundling is a thing, this will never happen.
Ok, let's define sufficient bandwidth. If you have 1000 customers on a node and they're all at your max tier, say 50 MB/s, you need 500,000 MB/s on that node to support theoretical peak bandwidth. Of course, the node will rarely if ever reach 500,000 MB/s and ISPs know this so, naturally, they'll do some percentage lower, say, 75% theoretical peak. They probably set this number based on a monthly (yearly, likely, or else I'd rarely have to complain about persistent bandwidth issues) report of max bandwidth in a node.
But, we're forgetting that until they upgrade those routers, their costs are mostly comprised of replacing aging hardware (ROFL) and paying employees, along with putting away billions for the CEO's severance package (I'm bitter). How does this differ from a shipping company who has to replace aging trucks, or purchase more trucks as their business grows? The analogy isn't 100% but it's a damn shot closer than Oreos vs. bits. If the actual peak bandwidth rises above "sufficient", then purchase more/bigger routers/another node for more customers.
An ISP is a business that, once it has a footprint, won't grow much. The ISPs around the US have carved out their own sections and detest anyone creeping into their regions. Thus, their expansion can and will flatline. How else are they supposed to grow their income? I can't fault them for wanting to do so but I can fault them their methods. That said, my electric company isn't growing its income.
It's past time ISPs become utilities or, better yet: must not control both the last mile and "first mile", and cannot be part of a content company.