You are right about power density,
If only we had an absolutely massive fusion reactor that could passively manage its own containment.
It would be so powerful that one such nuclear reactor would produce millions of times more power than we could ever consume.
The reactor could be designed to run indefinitely. No fuel or decommissioning costs incurred.
We could site the reactor at a large enough distance from population centers that we would not need to deal with its waste.
We could decouple the reactor from power generation. Just use safe EM radiation to freely distribute power wherever it would be needed.
The reactor itself, perhaps funded by some benevolent quadrillionaire, having no operating costs would be literally "too cheap to meter".