Yesterday, after wanting it for years, I finally found what looks like a good reference on what makes power plants so expensive. Most fusion-power proposals are based on using the fusion reactor to provide heat for a conventional thermal electrical power plant; https://www.eia.gov/analysis/studies/powerplants/capitalcost... gives a couple hundred pages of details about why those are expensive.
As I said in my comment at the time https://news.ycombinator.com/item?id=42850472, the cost of solar panels has dropped in recent years to the point where it's dramatically cheaper to generate electricity with solar than from a thermal power plant.
As I said in my comment at the time https://news.ycombinator.com/item?id=42850472, the cost of solar panels has dropped in recent years to the point where it's dramatically cheaper to generate electricity with solar than from a thermal power plant.