This isn't real right? I mean its a joke? It can't be a  serious offer, I am sure that this is just a rumor that was made to get some attention or something, to look that way. Otherwise we are talking about a billion dollar offer for a single season, that just doesn't make sense. It would be very fun however, because we would see one of the best players of current era, play against teams and players that are ten times worse than him easily, maybe more. I mean a 1 billion dollar player, going against 1 million dollar goalkeeper and defender lol, that would be fun to watch, like how we play FIFA and score 10 goals. All kidding aside, this would not make him a better player, he would be rich, never need money ever again, he could literally play for free after this, but would Real want a player that went to Al-Hilal for money? Maybe, he is Mbappe after all, but there will certainly be some suspicion.