They don't care about the lies they propagate secure in the knowledge that the royal family won't retaliate, certainly won't sue, and there are enough sycophants about to blame it all on the media.
Their aim is to cause as much distress as possible to Charles and William as they adjust to their new roles as King and Prince of Wales, in the hope of provoking an explosive reaction then Meghan can have the catfight she yearns for. There is no way back for them, and no use in appealing to their better nature, because they simply don't have one.