Imagine the cost savings in miniaturizing electrical grids.
https://www.moltexflex.com/flex-reactor/
A small fission reactor can do almost everything a fusion reactor can. Fusion fuel is higher density, but fission density is already not an issue.
Fusion still needs to heat water, that's where much of the cost comes from.
A fusion reactor does not pose environmental risk and could eventually run on highly available basic elements for everything after the initial "startup" once the technology progresses.
An fusion reactors don't actually run on basic elements. The require a fuel that is specially breed. And when they operate they have radioactive materials that can go airborn.
For me, the question here is: can we get our energy to cost 90% less than it did?
Don't get me wrong, I recognise that this is still a huge win (especially environmentally) and that it can have huge runway effects (eg. much more effective decentralization etc.) but it's quite interesting on how we can get these billions of people out of poverty first (or during).