Can someone explain why privacy coins like Monero are not more popular?
There is something going on in the cryptocurrency communities that doesn't reward features that increase privacy and decentralization. Privacy and decentralization should be the core incentives to use cryptocurrencies.
Regulatory pressure. With privacy comes illicit use. With illicit use, "what about the children / terrorism / etc..." becomes enough of a reason for regulators to pressure centralized exchanges to drop support. Without widespread adoption, centralized exchanges are needed to swap with more widely accepted monetary devices. If centralized exchanges are blocked, the on/off-ramp for privacy coins suddenly becomes much more difficult.
Why do you think the underground economy isn't more popular? I mean you can't get more privacy than that, no taxes, no regulations... it should be more popular right?
There is something going on in the cryptocurrency communities that doesn't reward features that increase privacy and decentralization. Privacy and decentralization should be the core incentives to use cryptocurrencies.