But after liberty reserve shut down they picked bitcoin.
Welcome to 2021, you seem to be stuck in 2013 ish. Nowadays the dark markets are back to fiat and anon altcoins and bitcoin has mostly been obsolete for illicit activities for years.
Now question is yes that time the stablecoins was not fully developed best ways ...but after the darkwebs and darkmarkets still used btc ltc and other volatility coins.
I don't see any question here. You made 2 statements that are weird at best but mostly wrong.
Even the stablecoins was stable why they took the risk to lose all their profit with btc volatility ?
Stablecoin creators have full control over their centralized altcoin and they produce that coin out of thin air and sell it to people for real money including fiat and bitcoin. That is 100% pure profit that you can't make any other way. But only profit for the makers of the altcoin.
If there was stablecoins wich was stable on value.
Is that they knew that btc will cost a lot more in future and they just holded and then contacted with big instutions who helping them sell it with higher price so from their black market actvities they can earn with btc 10x or even higher profit.
What does any of this have to do with darkweb?!!!