holy smokes tp you are a vegan too? Man this is scary. You and I seriously see eye to eye on a lot of stuff. I am a freakin' raw vegan. All I have eaten for the last 65+ years is raw fruit and veggie. I am not a rail. I am above the size limit of most of these chairs. They are mostly made for a certain percentile, bmi. That is smart financially for them as these are in fact expensive to produce and making huge chairs that do not sell is a waste to them. Although there are some very good big/tall chairs and these the price is insane but only part of it is markup. limited audience and cost a lot to make, Being over 7 feet tall and really buff actually has many disadvantages. Cannot change my height and I feel muscle is a heck a lot better than fat. Muscle weighs more than fat. Still, for my height I am not so heavy really. I would like a nice big/tall chair and even comfy but the price is a big deal.
As far as the big name brand chairs being haphazardly filed with glue,staples etc. that is not true I think. A really good one should look clean inside I would think unless I simply do not understand the construction of such an item. For instance if you look at good stereo amplifiers, even good Chinese made ones. Expensive to some but different price ranges. You wil find the good ones have all the wires routed tidy, soldering well done without too much flux etc. I do not know if this would apply to the very nature of chairs. A bunch of glue all over the inside, staples all over etc I am not sure if that is actually called for. He used this as a demonstration of them being poor quality. I saw several pictures of snapped in half Embodys on the net. I like the embody but simply way too big. The Aeron and Mira imo certainly are nice chairs. Other manufactures too. Bodybilt is great for hard to fit and comfy too but big money. First they charge $$$ just for a fitment session. Perhaps that very philosophy pays dividends though. Hardly any other company actually fits a chair. I mean you could get a aeron B not knowing you really need an A. The sales folk will usually sell the most expensive item that happens to be in stock. Not always if you trust them but often.
I understand proper posture may not be comfy but it does not absolutely have to be that way. I think bodybilt is great in this respect but will not spend that since multiple animals here will enjoy it as well. that is a specific issue to me however. It is stil hard to swallow on a chair. Other big/ tall chairs are still up there. I am not talking office depot or Ikea. Those simply are not good for your health. Health being important to me. I have the means to spend it but it seems absurd. I agree that China has us thinking differently. All of these are made in the most developed countries including US so of course they cost more to begin with.
I think the answer is to find something clean used. They are everywhere so no problem there. If well built they should last decades.
Some may be built better than others but either way the money is hard to swallow unless used. That seems the smart way to buy one. Tha I do not eat the depreciation someone else did.
One thing I would be very wary of is relax the back. They sell a little known chair, built to order. You can easily run it over 4 grand with options. It does not even appear to be a ergonomic chair but perhaps very comfortable. I don't know, have not tried it. There is most certainly no reason to spend that amount on that little known brand even if it is very good. Since you will unlikely find one used and you/me will take the huge depreciation hit. If one loves it then they have to consider but from the looks of it, it does not even promote proper posture.
One option for more average sized people may be the also little seen Recaro. They make the finest car seats. Although what makes a good car seat does not necessarily make a good office chair. A car seat is made to hold you put in those kind of cars.
Barring that you cannot find bodybilt used and would not get the fitment which may be key I shall just find a good clean used big/tall chair of the best I can. I have a very good chair that was fine for years but indeed the animals accelerated it's wear. Which is another reason It makes most sense for me to buy used. I do not need a brand new $$$ chair with a stain or tear the first week. Only serving to further decrease it's resale value. I cannot rightfully sell this now. I would say overall the smart thing to do is buy clean used. Since the huge price on these things plummets after initial usage. Just be careful there are, like everything else scammers out there. Sell you a destroyed chair for too much to begin with. Hopefully multiple pictures are present. The are also unscrupulous companies that will sell used/wron as new. If their new price is too low to be true, be wary.
That is my thinking on this subject and I apologize that it took me so many words to convey so.