The voters are the victims. No one cares if you pay off your mistress. Hiding it from coming out before the election by writing it off as a business expense in order to not have to report it to campaign finance is a crime.
The funny thing is he could have created reasonable doubt in the jury if he said that he only did it to hide it from his wife. Then it would have been a misdemeanor accounting violation. Instead he insisted on using the cover story in court that he didn’t know the woman, never had sex with her, and didn’t know anything about the money. No one was believing that.