I think what the poster is asking, is why wouldn't communities/darknet activites deal with other cryptocurrencies which are objectively better than Bitcoin in terms of functionality although they have a smaller community and network at the moment.
You guys are funny. Bitcoin is one of the largest currencies in the world with over 100 million users. Read the Bitcoin Standard to understand why.
I believe most markets already encourage the use of other privacy oriented tokens like XMR.
Pretty much all under the table crypto transactions are in Monero, Zcash, or other privacy coins. Bitcoin’s utility is horrible compared to most other cryptos, its purely a store of value.
I think BTC will always be a gambling ecosystem at minimum. There will be ebbs and flows between it crashing and spiking for its entire lifetime.