I think what many of us fail to grasp is this:
When some of us say we are in favor of decriminalization of most victimless drug crimes, we are not necessarily saying we condone drug use; we're not saying we think local street pushers should be allowed to pedal poison to our children or neighbors.
All we're saying is that we no longer wish to pay $40K per year to imprison someone for hurting themselves; nor are we willing to pay the costs of carrying that person's family on Welfare during the time of incarceration. We've done it for 4 Decades now and the percentage of US Citizens being jailed on our dime simply continues to mount. And we're tired of paying the costs to our civil liberties of the increasingly frenzied State Response to the Failed War on Some Drugs. The "preventive" benefit of the WoSD simply has never materialized; in Police Work, that would be called a "clue".
Think about it: Some guy wants to snort cocaine in a bathroom. You pay with your liberty to allow the State to get into that bathroom so that you can then pay his keep for 5 years; and his family's keep for the same duration. Now multiply that times a couple million families.
If someone wishes to kill themselves thru drugs, absent directly harming another, I simply don't see why I should be expected to pay to have them baby sitted for life.
As always, YMMV