What's the most unintentional monetary damage you've ever witnessed someone cause?

I fell off a stage while holding an HD broadcast camera in the early 00’s. Those were really expensive back then. Ruined about $160k worth of gear.

Once watched a non-technical manager destroy two flexible OLED prototypes in a row. At the time they were combined worth more than my yearly income.

That YouTube video of the guy knocking over every shelf in the warehouse at once

EDIT: I found a Montage

Whoever okayed the original Sonic Movie

Once worked in a shop where they built an entire massive pressure vessel, and only noticed once it was done that it was mirrored left/right from the blueprint.

Thankfully I wasn't involved in that particular project but yeeeesh, that probably cost nearly $100k to fix.

They had a multimillion dollar transit project near where I loved, like $112 million to replace a train station, a subway stop, and a major bus terminal to combine them into a single entity near Washington DC. They projected 3 years from start to finish, but it took almost 7. They had to reroute the entire bus terminal to surrounding streets and parking garages, which was a traffic nightmare. People using the train station or subway had to reroute their walk sometimes up to a mile off their present walk. While doing demolition, they found that the previous bus terminal was on the site of an old gas station which had been improperly sealed off: they just filled the tanks with concrete. Underneath that, they found tons of the the natural mineral serpentine, which naturally contains asbestos. So now they had a biological hazard which they had spent the last few months blowing up with dynamite into the surrounding city. After that was cleaned up and sealed, The got underway.

There were a ton of other mistakes, but when it was completed, they found defects. The superstructure is made of concrete and thus construction specifications were replete with engineering criteria for the composition of the concrete, and its pouring, curing and tensioning. The Inspector General systematically examined 22 project management and control points from the time concrete was mixed until the time it was ready for final inspection. 14 of 22 control points that should have minimized defects were weak or ineffective. Those defects may require recurring engineering inspections, higher maintenance costs, and they could shorten the planned 50-year useful life. In addition, the IG described the risk of concrete falling onto transit-center patrons.

The entire thing was a huge boondoggle costing the downtown untold millions into the future.

I only witnessed the aftermath, but I knew a guy that turned an end dump trailer upside down, twisting the frame on the truck and spilling 30 tons of diesel-contaminated soil in the ditch.

Apparently it cost a million bucks between cleaning that up and replacing the truck. (Mostly covered by insurance)

My brother knocked down our neighbor's front wall by accident (his vision was obstructed somehow) in his car. He had to pay for the whole thing to get replaced. Plus he had to get his car repaired too.

Not the highest monetary amount, but really well documented:

https://youtu.be/3GosoiF5NMk

We recently had a person from the hospital cleaning services throw away a 240k prosthetic limb. I felt really bad for the dude, because the prosthetist who was working with it is always super messy, and we do throw away a lot of weird looking stuff. The guy even tried going out to the dumpster and dug around for it.

We convinced the hospital not to fire the guy despite having to file a police report for insurance purposes. Unfortunately, he ended up being let go a couple months later for "unrelated" circumstances.

My dad started a bush fire ones..

Not sure of the value but looked bad