Pot, for example, grows out of the ground. It needs some sunlight, water, and maybe a little fertilizer.
How could any "Drug Lord" make money selling it? The enormous profits are only due to the legal risks.
The cost of manufacture and delivery of most other drugs would likewise be very minimal compared to today's artificially inflated prices.
How does Phillip Morris make enormous money selling tobacco?
Don’t be naive. The Cartel Drug Lords are mafia that control politicians, banks, hotels, resorts, casinos. They are not going to be stopped by silly people that think that legalization will solve all problems, far from it.
Pot and other drugs will be regulated and only those licensed to distribute will be allowed to sell it. The Cartels will kill their way to securing the distribution rights just as they do now in Mexico and also in the USA.
They also control prostitution, murder for hire, loan sharking and extortion.
You are playing with fire if you think legalization will make them go away.
Legalization will reduce their risks, secure their profits and allow them to gain revenue streams from addicting more and more users.
Again don’t be naive.