Well, because the person they are accusing admitted to assaulting women on video. In his very own words, he said he has done the exact thing these women are accusing him of. There is no better time to come forward than after your attacker has been recorded admitting (and bragging about) the crimes.
Besides… one victim has been fighting this losing battle for years. It’s hard enough to convict an average person. But convict Trump? Pretty much impossible. There would need to be evidence. An admission of guilt. …and we now have it on tape. Yet…people still don’t believe any of these women…even though he literally said he did it and we’ve all heard the proof.