Fusion, in any of its forms, requires some of the highest technology ever produced by mankind. It then exposes these ultra-high-tech wonders to extreme temperatures, and extreme temperature differences, and large amounts of extreme radiation (neutron bombardment), plus corrosion from the extremely fine hydrogen gas. Initial fusion power plants will operate at a very small energy efficiency, and they will need constant maintenance via high-tech robots capable of withstanding the radioactive environment that the neutron bombardment will create all around the reactor. Most pieces of the reactor will probably not last for more than a few months or at best years, due to all of the pressures described before.

Not to mention, the potential for catastrophic failure, though much less than with fission, is still enough to completely destroy the reactor and a good chunk of the plant, if the plasma containment fails. While of course incomparably safer than a fission reactor meltdown, it would still be a massive economic issue.

So commercial fusion, when it does finally arrive (or if), will be extremely expensive, with its only plausible use case as a somewhat reliable base load. Cheap fusion, if it is even possible, is much further away into the future than that - I would confidently bet that cheap fusion will not exist this century, even if ITER or others reach all of their milestones as planned.