Fiber isn’t that much. RDOF in the US is proving that it’s averaging about $1000 per home to lay fiber. Adjusted for inflation, that’s cheaper than copper was 100 years ago. At $80-$120 ARPU, the ROI is a few years at most.

I’d argue the issue is that these regulated monopolies are bloated to the point that they just don’t have the money to lay fiber.

Look at the cash sheets of all the ISPs… They all make the vast majority of their profits on the internet infrastructure and services, but blow it all on everything else they do… TV, VoIP, mobile VNO, sports teams rights, and other stupid crap.