It's not the morals I'm wondering about; it's the viability of the businesses. Investing in one of these companies is hoping you can cash out before the bubble pops. At least if you invest in a boring SaaS company, when the bubble pops, you might still have a boring SaaS company on the road to profitability.
If an exchange isn't misappropriating customer funds, it doesn't matter if the bubble pops. They facilitate transactions and take a fee in return. As long as they have customers and don't blow money all over the place, they should be profitable.
Risk management for traditional derivatives is hard, risk management for crypto derivatives is almost impossible.
Even if "exchange" doesn't misappropriating customer funds, the customers themselves can easily become insolvent in a moment, and then it will cascade to every other market participant.
If crypto stops appreciating, won't transaction volume collapse? I guess the question is how much crypto use is real (I'm sure there's a better word) and how much is speculative.