But many people get into drugs by choice, intentionally and willingly. Do they assume they have immunity from the bad side of drugs that effects other people? Have they not heard of, or do they disbelieve in, the addictiveness of drugs, and the deleterious effects of drugs on health? Maybe some people get into drugs as a ready means of escaping a drab and unpleasant existence - possibly as an alternative to suicide? Is the 'high' that drugs provide, still worth suffering the negative side of drugs, and so wonderful that a great many intelligent, ostensibly sensible, people jump in too. Is it true the high obtained from (all?) drugs diminishes over time, requiring an increased dose.
I don't NOT do drugs because I disbelieve the delightful effect claimed, but because I know that once I do, it will be the devil's own job extricating myself, supposing I retain a will to do so - plus I'm cheap, and drugs generally aren't.