Remember all the memes about how expensive lumber was? That was inflation in the price of lumber, driven mainly by residential construction because there's not a lot of wood in commercial or industrial construction anymore. They use steel for pretty much everything in those worlds, and our current trends of just in time manufacturing and building stuff after the order has been placed (on a bunch of stuff that's the only way it comes because it's custom designed) help drive steel costs way up.
Any time demand outstrips supply you have inflation, and construction has always been a different beast because once funding is secured and bids are won its go time, because delaying a job costs money as well because the company likely intends to repay the loan with the projects success. Bills are due for them as well, so delay is unacceptable and can ruin the project before they even get a chance to run it. Patents for manufacturing may depend on it, along with billions in profits, so imagine the world's worst Karen customer on every job. Projects often have completely unrealistic schedules, and since it's often rushed to market it's bid on with partial prints, and is being designed and engineered in almost real time, and as problems come up because drawing stuff on paper or a computer doesn't always work out in the real world. This is why most jobs run "over" estimates, it's often because they added a bunch of stuff thru the revisions, sometimes so much so it barely resembles the starting point. So even from an estimating point the amount of materials may not even be known, but once the process starts it can't be paused so the cost is more often ignored because the return will be high enough to justify the increased costs.
Companies had to mothball their projects for a few years because of covid, and many manufacturing facilities that supply the construction industry are still playing catch up. They had major outages and jobs that were shutdown because of hundreds of cases, and many of the other ones were pushed back or limited in scope to limit the headaches expected. Other jobs were done because the factory or offices had been shutdown, so construction could happen like crazy rather than being carefully scheduled. Borrowing money was very cheap, and so huge jobs with mountains of cash are finally going now, prices be damned they're all in. All of your engineers and the like were able to work remotely, so there's a huge backlog of work simply because of that too, all salivating to finally build the next big thing to make a ton of money. A bunch of people changed professions, so your gutter wage factory workers left in droves to find better jobs, further limiting the manufacturing sectors ability to catch up with the increased demand. Add in the massive chip and battery plants (and other gov work like bridges) and the demand for steel is likely to only increase for awhile.
These plants they're building are insanely massive, they're gonna be calling for literally thousands of fitters alone at each one, and because the pace of technology in that sector as soon as they finish they start all over retooling for the next gen, year after year. Since it was painfully obvious how bad globalization hit our supply chain there is going to be more manufacturing coming back for certain goods, so all of those will need even more steel. Of course no one has a clue how much exactly, but a lot of construction will be needed for building retrofits and new builds.
Since we're talking mini skids, let's look at why they have gone insane with prices. Most people see a baby skid steer or landscaping/tree care tool, but i see them differently because i work union construction. On a union job most pieces of dirt moving equipment are run by operators. The 1 giant exception to this of course is the mini skid, which when they came out were deemed too small to compete with a full size skid so they were awarded to the laborers, so companies could do small grading and backfilling jobs without a paying for an operator. As our electrical grid starting pushing renewable energy sources (especially wind), crane certifications became mandatory (even for small boom trucks now), and more and more road and bridge work started the operators wages have increased much faster and higher than the other trades, making mini skids even more valuable because of the increased cost savings. The minis got bigger and bigger, and now after covid everyone and their brother is trying to buy them, and since the jobs are going prices be damned they have to buy them prices be dammed too because they need the tools on the job today. This is why a full size skid is now cheaper than a mini sometimes. So not only did construction cause inflation, but specifically the wording in a union contract has, and has helped shape minis development as well to larger and larger machines rather than tighter space machines (and guess which costs more too!). These factors all drove up the price because the demand is still high enough to outstrip the supply enough to where they can't quite charge too much yet where it stops people from buying them.
That's the exact reason why the fed is raising rates, by making borrowing harder it should slow the rate at which loans are given, which slows the growth down enough where inflation is lower. Since once loan funding is secured for any project it's pushed to completion, the loans themselves are the basic driver of the entire economy, and the only way to slow it is to slow the loans. Interest rates have gone straight up, and begrudgingly it's forcing the cooling effect they need on the economy to slow the inflation. Basically we need to have a small recession to help restore the system to balance, kinda like letting a new engine idle a bit before you romp on it after a rebuild, but the delays in construction and companies necessity of completing projects won't let it yet. Wages are going up in order to get people, and that was even before covid in certain industries, all of which drives inflation.
So yeah, i think construction plays a pretty oversized role in this inflation thing. The last decade has seen large shifts in how we view the world, and the business landscape in America is changing in ways unforseen. Certain industries are in sharp decline while others are booming, and construction is up and is likely going to explode shortly when the system lag catches up. Wages have been driven by inflation already and continuing up, and for skilled trades by demand rather than union contracts lately, with the larger jobs in the country usually offering larger city rates and per diem to get the guys they need. Welders that can weld xray stuff are in very high demand, especially if you are willing to travel and hit the big overtime jobs. And as is tradition, we'll turn around and dump it right back in the economy, providing capital which is used for making new loans, which is how the economy grows, by forcing profits and growth or you get recycled.
Our recent tax cuts and stimulus shocked the system with a cash surplus which happened so fast it caused inflation, but that will also mix up wages which have been declining for decades, forcing employers to charge more and pay more and buy more, spreading money through the system. White collar workers are now seeing the possibility that they're likely to be replaced by automation quicker than the blue collar workers are, and with the coming chip revolution and ai becoming a reality we're up for some major changes ahead. The bottleneck to future growth will be energy, but if we finally crack the fusion problems it'll be growth like never seen, especially in construction. Construction is the first physical step in making more money in the cycle, and in my experience when it's banging the rest of the economy will be shortly if they aren't already, it seriously works like a leading indicator.
I've never seen mig wire for it (don't even know what shielding gas it requires) but I've run a bit of it tig welding, all for severe service in chemical plants (concentrated acids, etc). Did one whole tank once, cladded steel but the welds were all ate out, so we ground out all the welds and rewelded it all. Stuff welds like really dirty stainless, very sluggish and just wants to sit there rather than flowing, so much so that you kinda gotta use the wire to help move it the puddle where you want. Stupidly expensive stuff, as most really high alloys are. I would think it would bring good money if sold to the right person, maybe ebay or something? 
