Is an attempted "crime" a victimless crime? I don't believe it is. And I, of course, mean actual aggression, coercion, theft, or other violations of life, liberty, and property- not the ridiculous things The State seeks to forbid that have nothing to do with those real wrong things.
In order to attempt an initiation of force or theft, even if you fail to complete your intention, you have to have a target- a "victim"- in mind. That falls under threatening to initiate force, or violating property rights. Anyone on the receiving end of your intention to do them harm would not be wrong to use force to stop you from completing your intended action. How much force? How much will it take? How much adrenaline did your threat release in your intended victim, and how can you be sure "momentum" won't take them further than you think is "appropriate" under the circumstances?
But, as in the case discussed on the facebook thread linked above, the victim can't be imaginary or "society". That's like punching shadows. You may have an intention of doing someone harm, but there is no one there to be harmed.