Short answer:
Yes, derivatives allow farmers to lock in prices for their crops before they are harvested. They let businesses protect themselves against a rise in interest rates on their debt. There are numerous examples of how they are good and useful. They can be used prudently or inappropriately. There are so many types of "derivatives" that it hardly makes sense to lump them all into the same category. That's like putting oranges, apples, grapefruits and canteloupes in one basket.
IMO we do need more structure and regs for credit derivatives aka credit default swaps. Things like contract standardization, clearing house requirements, fuller disclosure. They were implicated in the 2008 financial crisis because AIG (an insurer, not a bank) sold them widely as an insurance product. Look up Joseph Cassano and the AIG Financial Products division in London. Cassano was a dumbfuck who didn't understand the product (credit default swaps) he was selling. Personally I am quite comfortable with 90% of derivatives but I still have issues with CDS.
Re. the current rider amending Dodd Frank, there are legitimate reasons the banks support it and there may be valid arguments against it (from adults like Sheila Bair, not childish idiots like Elizabeth Warren). I would need to hear both sides. What it's NOT about is gambling on the taxpayers' dime. The FDIC is funded with bank insurance premiums, not taxpayer dollars.
As for your question "how will it be different" - well, every economic or financial downturn is different. In 1998 it started with a Russian debt default and spread to a hedge fund named Long-Term Capital Management. In 2000/01 the tech bubble burst. In 2008 it was triggered by rising defaults on subprime mortgages. I can't tell you HOW the next crisis will be different, just that it will be. The business cycle will live on and regulators will again be fighting the last war. Capitalism isn't perfect but it beats the hell out of all the alternatives.
What is different and very dangerous this time around is that power-hungry left-wing demagogues and faux populists like Elizabeth Warren are exploiting false narratives about the financial crisis to push their dirigiste and redistributionist agendas. "Never let a crisis go to waste." That's what needs to be stopped.
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