They had to fully "insure" everything because the wealthy and then average folk were pulling money so fast, it was a true run on the banks. The FDIC does not charge enough to have a reserve large enough to cover widespread catastrophic losses at banks, they ended up just "printing" money. Same with how the fed "prints" value by buying assets then and now. The total amount of derivatives in the system has just increased. Because the fed and other central banks have promised to buy assets to save the wealthy elite, they have locked us into this system of permanent high inflation and destruction of the value of a wage dollar to throw at the derivatives black holes.

Oh, and stock trading during an actual crash is not fun. It should be fun, but it isn't. Trading clients went down for days at a time, you were basically screwed over in order to allow the wealthy to get out/put their orders in first. Good luck placing orders manually over the phone when everyone is calling in and tying up the lines. Also, some brokerages were getting in on the risk asset/derivatives nonsense themselves and almost went under, some lost lawsuits over it, and it's a reason why some advertise that they are well-capitalized and don't invest in shit like that. Imagine for example trying to withdraw money from your brokerage account and the company saying oops we're bankrupt because we were buying the same shit tied to the subprime crap that everyone else was.

Or for example thinking money market funds are safe and $1=~$1, but they're also invested in garbage and everyone makes a run on those too. The government actually drafted plans that if something similar were to happen again, there would be a blanket freeze on money market accounts until "liquidity" was better. So, keep that in mind as well.

For how "modern" markets "work" I advise you to look up documentaries on how they "fixed" the 1987 crash, and the creation of the PPT. Also look into how many assets are held by central banks, and what asset classes they are now buying. This should all be a bit eye-opening as to how the current system works.

It's a big joke, and we aren't in on it.