The risk is not just 'stabbed by a tweaker' but 'surprise fentanyl'. And police are very unlikely to come after some random online buyer who is not distributing/reselling.
If your sample is cross contaminated with fentanyl e.g. from a scale there is a chance the portion of the sample you sent for testing doesn’t have any fentanyl. These aren’t homogeneously mixed substances its someone loading a dime bag in a bedroom.
