Clearly there are some drawbacks to some of them, but alcohol and tobacco worse than some of them. Just think about it; it all comes down to personal responsibility so why prevent others from being happy? If you don't feel like smoking crack then don't, but don't stop another from wanting to satisfy themselves.
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The law does not just stop violence to people. The laws are there to protect any value that society deems previous enough to protect. That includes the safety of the self. Prostitution is illegal for a variety of reasons even though it is a 'victimless crime.' The law protects values society decides need protecting.