A plane toting a streamer reading “BI-DONE!” soared over a star-studded fundraiser in the Hamptons Saturday where the President was rubbing elbows with big-time Democratic donors. The opinionated aircraft flew from Montauk to Sag Harbor — made famous last week by Justin Timberlake’s DWI arrest — making sure to sweep past the ritzy event at the home of hedge-fund billionaire Barry Rosenstein and his wife Lizanne. Sources told The Post that a local Republican donor paid for the banner. Whether Biden himself saw the message is another story — he and First Lady Jill Biden spent the afternoon schmoozing with...
