I know nothing about your story, but based on what you said it sounds like it’s optimized already and the line-use fees+admin overhead pretty much explains why no one can offer better pricing. Again I know only what you wrote here, but that’s my uninformed opinion.
I don’t have a ton of knowledge in this area and am probably missing some things. But, I figured if they’re already able to offer 10G for $40/mo when they have to run their own physical infra on top of the peering and data center costs then they should be able to do it at a higher margin without. That higher margin could be a boon for them towards building their own infra in their current service area as well.
If they kept the same price then the total cost to the end user would be ~$70 for 10G. Which is less than half of the cheapest option available.