The number given in that article is 27 million slaves. Yet Wikipedia claims that 55 million people lived in the Roman Empire in AD 300-400. Were less than half of them slaves? (And that’s ignoring the slaves in the rest of the world at the time.) The same page claims that in 1750, the world population was almost 800 million. Were 29 out of 30 people at the time really free? Surely slavery was more widespread among the hierarchical city cultures that left written records than among the “barbarians”, but it’s hard to imagine that the number has always been less than 27 million. During the Middle Ages, throughout all of Europe, the vast majority of the people were serfs, bound to their land, living and dying at the mercy of their lords.
If it’s true that 249 out of every 250 people today is free, that sounds like a huge improvement over almost all of human history.
This doesn’t hold in general, and in fact doesn’t hold for your example. Cocaine has very rapid metabolism, and so withdrawal happens within a few hours of the last dose. From what I hear, typical symptoms include things like fatigue and anxiety, with anhedonia afterwards (which can last days to weeks). (Most of what is referred to as “cocaine withdrawal” is merely the craving for more cocaine.) By contrast, caffeine withdrawal often causes severe pain. Cocaine was initially believed to be quite safe, in part as a result of the absence of serious physical withdrawal symptoms.
Amphetamine and methamphetamine are probably the hardest drug in common use, so hard that Frank Zappa warned against them; withdrawal from them is similar to cocaine withdrawal, but takes longer, up to two weeks. Sometimes involves being depressed and sleeping a lot. As I understand it, it’s actually common for even hard-core speed freaks to stay off the drug for several days to a week at a time, because their body is too tired from a week-long run with no sleep. Often they stay asleep the whole time.
By contrast, in the US, alcohol is conventionally considered the second-”softest” of drugs after caffeine, and if we’re judging by how widespread its use is, it might be even “softer” than caffeine. But withdrawal from alcohol is quite commonly fatal.
Many “hard” drugs — LSD, nitrous oxide, marijuana (arguably this should be considered “soft”, but it’s popularly considered “harder” than alcohol or nicotine) and Ecstasy — either never produce withdrawal symptoms, or don’t produce them in the way that they are conventionally used. (For example, most Ecstasy users don’t take the pills every day, but only on special occasions.)