Your explanation of the Greek word pharmakeia shows poor scholarship.
I first heard of the "pharmakeia=drug use= sorcery" argument back in the early 1980's when I was involved with a Christian group. It never seemed right. The following is part of a word study I've done.
According to "Divry's English-Greek and Greek-English Dictionary" there are at least 19 different words having the root "pharma". Example's:
pharmakeia= poisoning; sorcery
pharmakeion= drugstore, pharmacy
pharmaki= poison, venom
pharmakon= medicine; drug; remedy
Apparently the meaning would depend on which inflection of pharma is used as well as context. Pharmakeia means poison and must not be confused with pharmakon which means medicine.
The above letter goes on at length in an attempt to prove that opium is a proper medicine and that Christians shouldn't fight a war against drugs.
Here is a classic example of someone arguing from the Greek without understanding the Greek language. Rather than argue, allow me to cite a reference work: The Complete Biblical Library: Greek - English Lexicon. The entries are based on the following resources: Strongs, Bauer, Moulton-Milligan, Liddell-Scott, and Colin Brown.
pharmakeia (noun): Sorcery, witchcraft, magic
pharmakeia: nominative singular feminine
pharmakeia: dative singular feminine
pharmakeion: genitive plural feminine
The family of words from which we get our English word pharmacy is derived from the Greek word pharmakeuo which means "to mix potions or poison." The term also refers to the practice of magic. Thus pharmakeia (also spelled pharmakia) refers to the practice of the arts associated with magic, which in the New Testament involved the use of potions or drugs. ...
pharmakeus (noun): Sorcerer, magician, poison mixer
pharmakeusin: dative plural masculine
This term, related to pharmakeuo, identifies those who practiced mixing potions, poisons, or drugs, i.e., magicians or sorcerers. ...
pharmakon (noun): Witchcraft, sorcery, magic potion, drug
pharmakon: genitive plural neuter
Classical Greek: Pharmakon is a noun which occurs in Greek literature form the time of Home (Eighth Century B.C.). In classical Greek it is used of a healing remedy or medicine, of a toxic drug or poison, and of a sedative or stimulative drug. Used figuratively it refers to an enchanted potion or to any means of attaining something. This latter meaning denotes a concoction made of various drugs and exotic ingredients that was used in the magical arts. In Herodotus 3.85 Oebares said to Darius, "No other man will be king but you; trust (my) pharmaka for that." This refers to magical formulas or charms such as used in witchcraft.
Pharmakon is often used for drugs, medicine, and poison in the papyri and in the writings of Josephus. Philo used it in the general sense of a remedy: "God holds out ... the most all-healing remedy" (On the Migration of Abraham 124). It takes occult connotations in The Shepherd of Hermas: "Be not like the sorcerers, for sorcerers carry their charms (pharmaka) in boxes, but you carry your charms and poison in your hearts" (Vision 3.9.7).
Septuagint Usage: In the Septuagint pharmakon means witchcraft, magical charms, poison, or medicine. ...
New Testament Usage: In the New Testament pharmakon occurs only in Revelation 9:21 in some manuscripts ... The reference is clearly to that which is an offense against God, i.e., the practice of magic or witchcraft. It most likely involved the use of drugs (magic potions) and the casting of spells. ...
pharmakos (noun): Sorcerer, magician, poisoner
pharmakoi: nominative plural masculine
pharmakois: dative plural masculine
The word only occurs once in the New Testament (Revelation 22:15). It refers to one who practices magical arts, such as mixing potions from herbs and exotic ingredients and muttering magical formulas or charms. The potions and enchantments did not have magical powers in themselves but were used to evoke the services of evil spirits. However, some potions were mixed as a poison. There is no essential difference between sorcery and witchcraft.