a fusion power plant the size of Earth’s moon, with the same power density as the Sun, could only power around 1 million US homes.

Capital costs alone are prohibitive.

TIL/google ai:

The power density of the sun at its core is about 276.5 watts per cubic meter ((W/m^{3})). This is similar to the power density of a compost pile, but lower than the power density of an adult human's metabolism.

ok. wow. But solar energy reaching earth can be converted to electricity by commercial PV at 250w/m^2. Even in US installed at under $1/watt with 50 years of useful output, and under 2c/kwh unamortized energy costs. That seems like the actual bar to pass, which is impossible for fusion or fission.