Court cases aren't about finding the truth - it's a game - in criminal trials it's a game as to whether the defendant's lawyer can create reasonable doubt - that's all they have to do, not prove innocence but create reasonable doubt regardless of whether their client actually committed the crime.
In civil cases there is a lower burden of proof, it will create loads of negative publicity for Andrew regardless of whether he is innocent and these cases can drag on for years and years with appeals. So it will be hanging over his head, and not only would he and his children and the rest of the family find it very stressful, Andrew would have been made to see that his extremely elderly and increasingly frail mother might not be able to cope especially now she has recently buried her husband and has to deal with Harry's anger at his father and the rest of the Royal Family - am assuming Andrew wouldn't want to be responsible for hastening his own mother's death due to stress.
Also, as a member of the Monarchy funded by the tax-payer Andrew can't do what he wants as those days are long gone. Presumably it was spelled out to him that he is mooching off the country and has to do what is in the best interests of the tax payer and the institution of the Monarchy (while it still exists) and if that means sacrificing his own reputation and retiring from public life by settling the civil case, which will lead to people thinking he is guilty of what Virginia Giuffre accused him of, so be it. I am sure Charles and WIlliam and others would have pressured him to settle. After all Andrew was the idiot hanging out with Epstein even after Epstein's criminal guilty plea and conviction and despite all the well-known allegations swirling around Epstein about trafficking under-age girls. Andrew was the idiot who did the 2019 BBC's Emily Maitlis interview where he said he did not regret his association with Epstein.
In 2015, Virginia Roberts said in a sworn affidavit that Maxwell initially approached her while she was working at Mar-a-Lago and offered to provide her with massage training. She was then brought to Epstein’s Palm Beach mansion, where she said Epstein abused her beginning in 1999, when she was 15 years old. She said the abuse continued for several years, during which she says she was passed around to other famous men.
Makes sense for Andrew to settle whether he is innocent of the accusation of forcing Virginia Giuffre to have sex against her will or even if he never had sex with her at all. As there has been no criminal trial it's a he said she said scenario and so Andrew is innocent of committing a crime in the eyes of the law, although he may have been found guilty in the court of public opinion.
Many people who can't afford to pay millions will take the pragmatic approach and settle in such situations where there is so much negative publicity against them. They pay less millions in a settlement than they would have to if they lost a civil case and they don't need to go through a long, protracted civil case and subsequent appeals with the associated huge legal costs. I know I would settle in those circumstances, especially where I have been a colossal entitled idiot, even if I was innocent of the actual sex allegations. I would chalk it up to the price you pay for being a public figure with deeper pockets than the claimant. Virginia Giuffre was trafficked and someone in the establishment needs to pay - it might as well be Andrew if she happens to have a photo of him with his arm around her, even if she can't provide the original photo for examination to back up her claim. In the current #Me Too climate the accusation and the photo is enough to put Andrew in serious danger of losing a civil case (as opposed to a criminal one with its higher standard of proof).