1) Hand-wavy exchange of money. Most of the derivatives market, including some of the most traditional instruments like energy Futures, have massive amount of cash-settled activity, rather than physically-settled -- ie. nothing physical is actually exchange hands, and traders are purely exchange financial risk.

That doesn't make the transaction any less important and valuable: at the end of the day, participants are hedge financial exposure and cash-settlement is a great and more efficient way to get that hedge in.

2) Single-point of failure OR arbitrary change to the underlying. There's an extreme amount of scrutiny and safeguards around how CPI is calculated and how it is changed. CPI impacts trillions that are traded in traditional assets like interest rate swaps, inflation swaps, mortgages, etc. Also, CPI is a large factor in the Fed's decision to raise interest rates at every meeting. It cannot be changed by a single person, on a whim. And this tends to be true for all the data sources underlying our markets.

Arguably, a stock has much more key man risk (or "arbitrary whims risk") than something like CPI: eg. Elon ripping a bong and tweeting something's impact on Tesla stock.

3) More like roulette than actual investment. The lack of physical underlying doesn't make this any less of a financial instruments. Most liquid markets today do not actually exchange the underlying, eg. interest rate swaps, index futures, etc.

What differentiates a financial product from gambling is the presence of an economic purpose. A roulette spin does not need to happen - it happens solely to create an artificial risk for people to bet on. In the case of event contracts, things like an election or a CPI print already expose the market to risk... that risk already exists and our markets allow the transfer of said risk from people that have and can't bear it to people that have the appetite to bear it (that's actually the whole point of the commodity futures and derivatives market).