The quality of life of a human being is directly related to the amount of free energy (i.e. thermodynamic free energy, not free as in no cost) they have access to. Life must be able to generate more energy than it needs, even tiny bacteria. As humans developed, we found more ways to access and utilize free energy.
There is a phrase: Energy return on investment (or EROI). You can map the development of humanity pretty cleanly to an increasing EROI over the entire course of our history.
Fossil Carbon allowed us to explode our EROI and gave us access to never before seen amounts of free energy. Unless we find ways to maintain that EROI, our quality of life will necessarily diminish.
Obviously we need to cut our use of fossil carbon. And if we don't, we're simply going to run out, and then we'll be stuck anyway. But we also don't have anything with a comparable EROI to replace it with.
This is the root problem we're facing. If we had working fusion, it would be a whole lot easier to decarbonize.
And it was the cheapest way only because most prices are fake, because they do not correspond to the cost of closed cycles of the materials used to make a product.
All those things require mostly energy, air, water and a few abundant minerals and metals to be made. Technologies to make them in this way have already existed for almost a century (e.g. making synthetic hydrocarbons, to replace oil), but they are still very inefficient. However, the inefficiency is mostly due to the fact that negligible amounts of money have been allocated for the development of such technologies (because as long as the use of fossil oil is permitted, there is no way for synthetic hydrocarbons to be cheaper), in comparison with the frivolous amounts of money that are wasted on various fads, like AI datacenters.
The fact that fossil fuels -- since their mass adoption in the late 19th century -- are the single largest cause of improved living conditions is standard economic history.
> An unsustainable solution is not in-fact a good solution.
It was a perfectly good solution. It replaced wood fires which are clearly worse. Coal was great until natural gas became available. As solar/wind/nuclear become abundant, they are conintuing to displace fossil fuels.