Communication is a difficult thing, especially written communication. I work proactively to get better at it when the opportunities to do so arise.
In your initial response, and in this one, what I "hear" is that what you heard was somehow either dismissive or disrespectful of the experience the OP brought to the table. I am interested in understanding what it was about my words that gave you that impression. I do understand that reality is very complicated and building systems as ones $dayjob in a competitive environment gives you a depth of knowledge that is unmatched.
What I heard in the OP comment was a question, "What makes fusion different?" and in this case the context was why might it be a step change versus other things (some of which the author was involved in) have not gotten traction. And the specific driver was how to compete with costs from extractive technologies like natural gas that are quite mature.
I shared my point of view and reasoning from the perspective that I expected the ratio of the plant construction and operation cost relative to the energy output to be much higher than pretty much any other technology so it's LCOE will be lower.
Do I know that to be the case? No I don't. Can I reason to that position from first principles? I think so, and calling me out on my reasoning as pfdeitz has done a couple of times in this thread is awesome (the most relevant for this thread being that so far we only know how to make fusion plants with a much lower energy/m3 ratio than say nuclear plants)
To your comment about 'whom to believe' I would say I'm not asking you to believe me (and I hope that wasn't a take away from my responses). I was sharing how I thought fusion was different, others have other takes on this, and nobody knows for sure because well it doesn't exist yet. I am curious though, if you feel okay sharing it, if there is anxiety with your belief system.
When I am presented with information and I don't know how much confidence to put into it, I often do similar things which is to look at the source, and to consider how the source arrived at that belief. Ideally I like to hear how they got to that belief which probably comes from reading a bunch of scientific papers that are basically one long essay that use the form: "This is what we believe, this is why we believe it, and this is the evidence we have to support our beliefs." But even in a paper I still hold that belief "lightly." If you see me passing such things on it will usually be of the form, "here is a reference to a paper or article I've read that posits this." As opposed to some definitive statement of truth. For me, I'm not invested in being "right".
I can easily say that most of the best conversations I've had, started with "Chuck you are completely wrong about that and here's why ..." I love conversations like that because it means I'm likely to learn something new, and every time we re-examine what we "know" we often come away with a better understanding of the limits of what we "know" and what we "think" or hypothesize.
Throughout this conversation it has been my intent to be clear that these are things I "think" based on what are, to me, comparable but "solved" problems. Still there are a lot of unknown unknowns such as it is and everything I think could easily be invalidated by one of them. I am always on the lookout for this sort of information. It helps keep me grounded.
Always working on improving communications and critical thinking skills and always open to feedback.