The offer was deferred money. The Phillies and the other teams bidding for him were not. The Lerners offer was a joke. Would you prefer $300 million paid out over 20 years on a ten year contract or $330 million paid out of over 13 years on a 13 year contract? The Lerners knew he and Boras would turn it down.
Harper did not have the Fillies offer when he turned down the Nats. He had no offer. Not from anybody until just before Spring Training. He appears to have come back to the Lerners in December, 2018, asking if the offer was still on the table. It wasn't: the Nats had already spent big on Corbin and a few secondary players.
Harper lost out. He lost a chance to play alongside Soto and Rendon and Turner and Zimm / Howie, and behind Scherzer and Strasburg. He made a little more money, and "won" the pride of having gotten the largest contract, at the time, of any ballplayer. That proud moment went quickly, and now he has the pride of playing for the team that had less than 50% of players get vaccinated. And missing the playoffs again.