I think you’re getting hung up on the figurative language. A “sin tax” isn’t about a religious sin, it’s about taxing something that’s obviously bad, but not harmful enough to justify criminalizing it and often popular enough that people would be outraged if you just banned it. Like cigarette taxes, weed taxes, alcohol taxes and the like. Things that not only harm you, but the community that then has to deal with the consequences of your choices.

The idea is those taxes then go to fund mitigation programs. Rehab, or gym membership tax credits or things like that.