Well, a dolar is still a dollar and they need to sell on the same energy market. It's well understood that fission projects have become economically infeasible because they are dominated by capital costs, and the risks these projects come with are not compatible with the decades required for economic breakeven.

Everything we know about current approaches to fusion seem to indicate they will have the same economic problems. The scaling factors of confinement, power and reaction rates push towards immense reactors with vacuum chambers the size of apartment buildings, massive superconducting magnets etc. hence the ITER project spiraling out of control trying to build one just big enough that at least have a fair chance of achieving engineering breakeven. The basic plasma physics works the same for Helion, and the best triple product they achieved places them two orders of magnitude behind tokamaks, albeit with much less capital.

So when and if the best approaches to fusion succeed, it looks like they will yield these massive plants that share the costs problems of fission. While they won't be able to meltdown, the regulatory constraints will be very similar, the intense neutron flux will activate the structure of the reactor and poses similar proliferation and decommissioning concerns, there is radiological risk to the civil population in the form of Tritium leaks etc.

And unlike fission, which is very well understood and mature, fusion plants will be much riskier economically, on par with the attempt to introduce fast fission breeders into commercial service, which notoriously failed.

So while the physics is indeed very different, we know enough to compare fusion and fission economically, and the outlook is very bleak.

Why do you think fission plants are expensive? Do you think it's the pumps and turbines and concrete?

Pro tip: it's not. It's because there is millions of man-hours of regulatory burden attached to every decision, to every bolt, to every instrument or valve installed.

There is a reason for all that regulatory burden, of course. It's the release of long lived and deadly radiation from a meltdown. If it wasn't for that regulation building a nuke plant would actually be quite inexpensive, relative to current costs- On the scale of a hydro dam.

Fusion has none of those costs because it has none of the same dangers. It's a wildly different problem with wildly different cost basis. The expensive part is research. Once that's done that cost is gone.