The idea of DIY sharing of a leased line bewteen neighbours is, like J0hn83 says, a non starter - for many reasons.
The apparent costing may look doable on paper, but it is a naïve, idealistic and simplistic argument.
Even if the equipment were cheap and readily available, which it will be to some people, the real problems with the idea are more basic:
First and foremost, Money - sharing the cost of anything between friends, family let alone neighbours causes friction - the "Well I didn't have any wine" after a meal is all too familiar.
Distribution - the actual sharing is going to rely on a wireless solution one way or another in reality for most properties and this will cause issues and add costs both in installation and support and most likely speed and reliability as well.
The "What if" factor - What if the host moves house, what if someone drops out, what if the host changes their mind about sharing, what if someone is doing illegal file sharing or being used to host a DDOS attack... the list is endless.
Local or community sharing of a service like this is just not the same as sharing within a household or an office environment.
They may not realise it, but end users actually like and need independence of support and a choice of provider, and like Electricity, Gas and Water - we simply don't go around sharing it with our neighbours like that.
Trust - who really wants to put their internet access in the hands of fred 3 doors down? Are they watching your traffic, monitoring your dns? Yes all these can be addressed - but it is just not worth the hassle.
Edited by TechGuyUK (Mon 15-Nov-21 12:25:50)