If this were a factor, then why would Delta and AA have multiple fights daily and on weekends between NYC and DCA? Amtrak isn't always the most reliable or convenient option for people in the NYC area. Unless you actually live in Manhattan or one of the outer boroughs, it can actually be out of the way to get to Penn Station versus just going to the airport and hopping on a 40 min flight. And often, the flights are comparable in price if not cheaper than Amtrak. I haven't taken a train to DC in years because it's just not convenient to where I live.