what do you mean how does it harm me? if spitzer stole $10 from Bob Smith, it doesn’t harm you either because he didn’t steal from you.
Maybe we should legalize stealing. It could be regulated so that it is ok to steal items less than $5. Most people don’t care about anything less than $5 anyway. So let’s make it officially legal and give an outlet for those kleptomaniacs who feel like pickpocketing spare change every once in a while.
Your example is ridiculous. If he steals from another, he might steal from me or you, and that harms us. In any case, he did steal from the other, and should be punished (or better, should make good).
If someone diddles a willing prostitute, that in and of itself doesn’t harm the prostitute (who was willing, remember), nor does it increase the risk the person will want harm you or I.
But if you establish precedents that government should restrict certain behaviors, that DOES harm me because government never, ever stops at the limits first imposed on it, and now there are innumerable laws against other things, that infringe on my liberties - and yours too if you would look.