There are gangs and violence all along the supply chain. The online marketplace only removes the last (few hundred) miles.

So it's much safer for customers and will likely reduce drug violence?

It's not that simple. It might still be a net negative if it increases drug demand by ease of access.

I don't think you increase demand by ease of access.

Also buying bitcoin, exchanging to Monero, installing Tor, understanding the risks, etc. Is much more work than just finding the next dealer.

> I don't think you increase demand by ease of access.

Well that's the entire principle of price elasticity. The less costly (not only in terms of money, but also in terms of risk and time) something gets the higher the demand, at least up to a point.

> Don't online drug marketplaces lead to reduced gang activity?

Online isn't the important factor here.

> One does not need a gang and violence to sell drugs online.

Gangs and violence aren't there to support a marketplace. They don't help you find customers or customers to find you. They don't improve the efficiency of exchange. They're there to enforce outcomes. Selling drugs leads to outcomes that don't care whether the buyer and seller found themselves online.