Supposing you're discussing in good faith, I'll engage with you, and _agree_: for the near term, I do not believe that fusion will be a commercially viable competitor to wind and/or solar. Not within 10, 20, 30, or even 50 years. I also agree that it likely won't beat the dollar-cost of fission power in that timeframe. But I do think it will replace fission for most new power projects somewhere within that timeframe, especially in developing nations.
The expensive thing about fission is not getting a fission reactor to work, nor keeping it running. It's in getting the reactor greenlit at all, bespoke-designed, and handling supply and waste management. In many places, it is simply not an option due to geopolitics. So fission problem is not impractical because it is cost-prohibitive. Instead, it is impractical because it is responsible-waste-management and weapons-proliferation-regulations and spooky-stuff-difficult-political-battle-PR-nightmares-prohibitive. Sadly, very few people a) want a nuclear reactor in town, b) want to shoulder the risk of building, maintaining, and staffing a fission plant for 50 years, or c) want any "risky" nations to have easy access to them. That, far more than dollar-cost-per-megawatt-hour, is why we don't have nuclear plants everywhere today.
Solar and wind are amazing, and obviously essential to any future we have, but today they cannot do everything, everywhere. Further revolutions in power storage and transmission might enable that (like huge flywheels?) but that's not what we're discussing, we're discussing whether fusion a) can work, b) is useful at all, and c) will ever see large scale use for power production. I do grant that it's _possible_ that a flywheel-revolution could outpace a fusion-revolution.
Because of fission's problems, the niche of fusion over the next 30-50 years may be "nuclear power, but safer": it's more expensive, but it can be sold or built anywhere, the fuel control is not so vital/tough, and the waste is handleable on a timescale we can _at least_ wrap our heads around. Wind and solar currently need baseline plants for supplementation, and fusion may be the ticket to turning off the last remaining gas and coal plants out there, or in supplying power to underpowered nations with less favourable conditions for wind and solar. That is wonderful! That is lightning in a goddamned bottle. Literally! Does it have to be the cheapest option, when for many it's the only option?
Past 50 years, well, history would suggest it'll likely get better. Fission would likely be a lot better today (read: cheaper, smaller) if it were safer to begin with, and solar and wind have gotten astoundingly cheap as they've seen investment and use expand over time, so why shouldn't fusion do the same?
So the argument is: we're now likely to get net-positive tokamaks by ~2030. And if we have any net-positive tokamaks by 2030, then they can likely fill a power-niche that fission just can't. And if we spend 50 years making fusion plants and proliferating the technology, by 2080 it might get pretty damn cost effective. I think that's the bet all these smart people are making, and personally, I'm inclined to take it.